View Code of Problem 51

import java.util.Scanner;
public class Main{
     public static void main(String []args){
         Scanner scanner = new Scanner(System.in);
         int n = scanner.nextInt();      
         int a[][] = new int [n][n];   
         for(int i = 0; i < n; i++)   
         {
             for(int j = 0; j < n; j++)   
             {
                 a[i][j] = scanner.nextInt();
             }
         }
         int sum = 0;
         for(int i = 0; i < n; i++){
             for(int j = 0; j <= i; j++)    
             {
                 sum = sum + a[i][j];
             }
         }
        System.out.println(sum);   
     }
}