#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,a[2005][2005],x,y;
signed main() {
	scanf("%lld",&n);
	for(int i = 1;i <= n;i++) {
		for(int j = 1;j <= n;j++) {
			scanf("%lld",&a[i][j]);
			if(a[i][j] == -1) x = i,y = j;
		}
	}
	if(x < n and y < n) {
		printf("%lld\n",a[x + 1][y] + a[x][y + 1] - a[x + 1][y + 1]);
	}
	else if(x == 1 and y == n) {
		printf("%lld\n",a[x + 1][y] + a[x][y - 1] - a[x + 1][y - 1]);
	}
	else if(x == n and y == 1) {
		printf("%lld\n",a[x - 1][y] + a[x][y + 1] - a[x - 1][y + 1]);
	}
	else {
		printf("%lld\n",a[x - 1][y] + a[x][y - 1] - a[x - 1][y - 1]);
	}
	return 0;
}