#include<stdio.h>
int main() {
int arr[10][10] = { 0 };
int i = 0;
int j = 0;
int n = 0;
scanf("%d", &n);
int sum = 0;
for (i = 0; i < n; i++) {
for (j = 0; j < n; j++) {
scanf("%d", &arr[i][j]);
while (i > j) {
sum += arr[i][j];
break;
}
}
}
if (sum == 0) {
printf("YES\n");
} else {
printf("NO\n");
}
return 0;
}



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