#include<stdio.h>
int d[2][2222]={0},a[2][2222]={0},n;
int min(int a,int b){if(a<b)return a;return b;}
int f(int a,int b){if(a>b)return 0;return b-a+1;}
int main()
{
int i,j;
scanf("%d",&n);
for(i=0;i<n;i++){
for(j=0;j<n;j++){
scanf("%d",&a[i%2][j]);
if(!i && !j) continue;
else if(!i) d[i%2][j] = d[i%2][j-1]+f(a[i%2][j-1],a[i%2][j]);
else if(!j) d[i%2][j] = d[(i+1)%2][j]+f(a[(i+1)%2][j],a[i%2][j]);
else d[i%2][j] = min(d[(i+1)%2][j]+f(a[(i+1)%2][j],a[i%2][j]),d[i%2][j-1]+f(a[i%2][j-1],a[i%2][j]));
}
}
printf("%d",d[(n-1)%2][n-1]);
return 0;
}
