View Code of Problem 51

#include<cstdio>
#include<iostream>
#include<algorithm>
#include<cmath>
#include<cstring>
#include<vector>
#include<map>
#include<string>
#include<set>
using namespace std;
int a[100][100];
int main()
{
    int n;
    cin>>n;
    int sum=0;
    for(int i=0;i<n;i++)
    {
        for(int j=0;j<n;j++)
        {
            cin>>a[i][j];
            if(i>=j)sum+=a[i][j];
        }
    }
    cout<<sum;
	return 0;
}