View Code of Problem 51

#include<cstdio>
int main(){
	int n,a,sum=0;
	scanf("%d",&n);
	for(int i=0;i<n;i++){
		for(int j=0;j<n;j++){
			scanf("%d",&a);
			if(i>=j)	sum+=a;
		}
	}
	printf("%d",sum);
	return 0;	
}