diff --git a/660.cpp b/660.cpp
new file mode 100644
index 0000000..043952a
--- /dev/null
+++ b/660.cpp
@@ -0,0 +1,61 @@
+#include <bits/stdc++.h>
+#define IOS                  \
+	ios::sync_with_stdio(0); \
+	cin.tie(0);              \
+	cout.tie(0);
+#define endl "\n"
+#define ll long long int 
+#define pb push_back
+#define pf push_front
+#define ma make_pair
+#define f1(i, a, b) for (int i = a; i < b; i++)
+#define f2(i, a, b) for (int i = a; i > b; i--)
+#define ff first
+#define ss second
+#define lb lower_bound
+#define ub upper_bound
+#define mod 1000000007
+#define ii pair<int,int>
+#define vi vector<int>
+#define vl vector<ll>
+#define vii vector<ii>
+#define pq priority_queue<int,vi,greater<int> > //for min heap.
+using namespace std;
+vector<ll> primefactor(ll n)
+{    
+    vl prime;
+    for(ll i=2;i*i<=n;i++)
+    {   if(n%i==0)
+        { 
+           while(n%i==0)
+          { prime.pb(i); n/=i;}
+          
+        }
+    }
+    if(n>1) prime.pb(n);
+    return prime;
+}
+bool t(ll a,ll b,ll c)
+{
+    if((a+b)>c&&(b+c)>a&&(c+a)>b)
+    return true;
+    return false;
+}
+int main()
+{  IOS;
+   int t;
+   cin>>t;
+   while(t--)
+   {
+       int n;
+       cin>>n;
+      int x=ceil(1.0*n/4); // no of 8 ;
+    //   no of 9 = n-x;
+      for(int i=0;i<n-x;i++)
+      cout<<9;
+      for(int i=0;i<x;i++)
+      cout<<8;
+      cout<<endl;
+   }
+ 
+}  
diff --git a/766.cpp b/766.cpp
new file mode 100644
index 0000000..165d436
--- /dev/null
+++ b/766.cpp
@@ -0,0 +1,63 @@
+#include <bits/stdc++.h>
+#define IOS                  \
+	ios::sync_with_stdio(0); \
+	cin.tie(0);              \
+	cout.tie(0);
+#define endl "\n"
+#define ll long long int 
+#define pb push_back
+#define pf push_front
+#define ma make_pair
+#define f1(i, a, b) for (int i = a; i < b; i++)
+#define f2(i, a, b) for (int i = a; i > b; i--)
+#define ff first
+#define ss second
+#define lb lower_bound
+#define ub upper_bound
+#define mod 1000000007
+#define ii pair<int,int>
+#define vi vector<int>
+#define vl vector<ll>
+#define vii vector<ii>
+#define pq priority_queue<int,vi,greater<int> > //for min heap.
+using namespace std;
+vector<ll> primefactor(ll n)
+{    
+    vl prime;
+    for(ll i=2;i*i<=n;i++)
+    {   if(n%i==0)
+        { 
+           while(n%i==0)
+          { prime.pb(i); n/=i;}
+          
+        }
+    }
+    if(n>1) prime.pb(n);
+    return prime;
+}
+bool t(ll a,ll b,ll c)
+{
+    if((a+b)>c&&(b+c)>a&&(c+a)>b)
+    return true;
+    return false;
+}
+int main()
+{  IOS;
+ 
+       ll n;
+       cin>>n;
+       vl a(n);
+       for(ll i=0;i<n;i++) cin>>a[i];
+       sort(a.begin(),a.end());
+       bool f=false;
+       for(ll i=0;i<n-2;i++)
+       {
+           f=t(a[i],a[i+1],a[i+2]);
+           if(f)
+           {   cout<<"YES"<<endl;
+               break;
+           }
+       }
+       if(!f) cout<<"NO"<<endl;
+ 
+} 
diff --git a/90a.cpp b/90a.cpp
new file mode 100644
index 0000000..5fff316
--- /dev/null
+++ b/90a.cpp
@@ -0,0 +1,53 @@
+#include <bits/stdc++.h>
+#define IOS                  \
+	ios::sync_with_stdio(0); \
+	cin.tie(0);              \
+	cout.tie(0);
+#define endl "\n"
+#define ll long long int 
+#define pb push_back
+#define pf push_front
+#define ma make_pair
+#define f1(i, a, b) for (int i = a; i < b; i++)
+#define f2(i, a, b) for (int i = a; i > b; i--)
+#define ff first
+#define ss second
+#define lb lower_bound
+#define ub upper_bound
+#define mod 1000000007
+#define ii pair<int,int>
+#define vi vector<int>
+#define vl vector<ll>
+#define vii vector<ii>
+#define pq priority_queue<int,vi,greater<int> > //for min heap.
+using namespace std;
+vector<ll> primefactor(ll n)
+{    
+    vl prime;
+    for(ll i=2;i*i<=n;i++)
+    {   if(n%i==0)
+        { 
+           while(n%i==0)
+          { prime.pb(i); n/=i;}
+          
+        }
+    }
+    if(n>1) prime.pb(n);
+    return prime;
+}
+int main()
+{  IOS;
+   int t;
+   cin>>t;
+   while(t--)
+   {
+       ll a,b,c;
+       cin>>a>>b>>c;
+       if(a<c)
+       cout<<1<<" ";
+       else cout<<-1<<" ";
+       if(c<a*b)
+       cout<<b<<endl;
+       else cout<<-1<<endl;
+   }
+}
diff --git a/building.cpp b/building.cpp
new file mode 100644
index 0000000..3a102df
--- /dev/null
+++ b/building.cpp
@@ -0,0 +1,83 @@
+#include <bits/stdc++.h>
+#define IOS                  \
+	ios::sync_with_stdio(0); \
+	cin.tie(0);              \
+	cout.tie(0);
+#define endl "\n"
+#define ll long long int 
+#define pb push_back
+#define ma make_pair
+#define f1(i, a, b) for (int i = a; i < b; i++)
+#define f2(i, a, b) for (int i = a; i > b; i--)
+#define ff first
+#define ss second
+#define lb lower_bound
+#define ub upper_bound
+#define mod 1000000007
+#define ii pair<int,int>
+#define vi vector<int>
+#define vl vector<ll>
+#define vii vector<ii>
+#define pq priority_queue<int,vi,greater<int> > //for min heap.
+using namespace std;
+vector<int> arr[100001];
+bool vis[100001];
+int col[100001];
+int dx[4]={-1,0,1,0};
+int dy[4]={0,1,0,-1};
+// bool isvalid(int x,int y)
+// {
+//     if(x<1||x>n||y<1||y>m)
+//     return false;
+//     if(vis[x][y]==true||ar[x][y]=='#')
+//     return false;
+//     return true;
+// }
+bool dfs(int node,int c)
+{
+    vis[node]=1;
+    col[node]=c;
+    for(auto child :arr[node])
+    {
+        if(!vis[child])
+        {
+            if(dfs(child,c^1)==false)
+            return false;
+        }
+        else
+        {
+            if(col[node]==col[child])
+            return false;
+        }
+    }
+    return true;
+}
+int main()
+{
+    int n,m,a,b;
+    cin>>n>>m;
+    while(m--)
+    {
+        cin>>a>>b;
+        arr[a].pb(b);
+        arr[b].pb(a);
+    }
+    bool f=true;
+    for(int i=1;i<=n;i++)
+    {
+        if(!vis[i])
+        {
+            f=dfs(i,0);
+            if(f==false)
+            break;
+        }
+    }
+    if(!f) cout<<"IMPOSSIBLE"<<endl;
+    else
+    {
+        for(int i=1;i<=n;i++)
+        cout<<col[i]+1<<" ";
+        
+    }
+    
+}