- #include <iostream> 
-   
- using namespace std; 
-   
- int main() 
- { 
-     int n; 
-     cin >> n; 
-     int k, l=0; 
-     for(int i=0;i<n;i++){ 
-         for(int j=0; j<n; j++){ 
-             cin >> k; 
-             if(k) 
-             l++; 
-         } 
-     } 
-     cout << l << endl; 
-   
-     return 0; 
- } 
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