View Code of Problem 51

    #include<stdio.h>
    #include<string.h>
    #include<math.h>
    int main()
    {
    	int n;
    	scanf("%d",&n);
    	int a[n][n];
    	int i,j;
    	for(i=0;i<n;i++)
    	{
    		for(j=0;j<n;j++)
    		{
    			scanf("%d",&a[i][j]);
    		}
    	}
    	int sum=0;
    	for(i=0;i<n;i++)
    	{
    		for(j=0;j<=i;j++)
    			sum+=a[i][j];
    	}
    	printf("%d\n",sum);
    }