Codeforces 69A

#include <stdio.h>
int main()
{
    int n;
    int sum1=0, sum2=0, sum3=0;
    int x, y, z;
    scanf("%d", &n);
    int i;
    for(i=0; i<n; ++i)
    {
        scanf("%d %d %d", &x, &y, &z);
        sum1+=x;
        sum2+=y;
        sum3+=z;
    }
    if((sum1==0)&&(sum2==0)&&(sum3==0))
        printf("YES\n");
    else
        printf("NO\n");
    return 0;
}