#include <cstdio>
#include <algorithm>
#include <cstring>
using namespace std;
int a[2500][2500],n;
int dp[2500][2500];
int main(){
memset(a,0x3f,sizeof(a));
scanf("%d",&n);
for(int i=1; i<=n; i++){
for(int j=1; j<=n; j++){
scanf("%d",&a[i][j]);
}
}
for(int j=2; j<=n; j++){
dp[1][j] = dp[1][j-1] + max(a[1][j]-a[1][j-1]+1,0);
}
for(int i=2; i<=n; i++){
dp[i][1] = dp[i-1][1] + max(a[i][1]-a[i-1][1]+1,0);
for(int j=2; j<=n; j++){
dp[i][j] = min(dp[i-1][j] + max(a[i][j] - a[i-1][j]+1,0),dp[i][j-1] + max(a[i][j] - a[i][j-1]+1,0));
}
}
printf("%d",dp[n][n]);
}
