#include<cstdio>
#include<algorithm>
int a[2222][2222];
int main()
{
int i,j,n,r=0;
scanf("%d",&n);
for(i=0;i<n;i++)for(j=0;j<n;j++)scanf("%d",&a[i][j]);
i=j=0;
while(i!=n-1||j!=n-1)
{
if(i==n-1)
{
r+=std::max(a[i][j+1]-a[i][j]+1,0);
j++;
}
else if(j==n-1)
{
r+=std::max(a[i+1][j]-a[i][j]+1,0);
i++;
}
else
{
if(std::max(a[i][j+1]-a[i][j]+1,0)<std::max(a[i+1][j]-a[i][j]+1,0))
{
r+=std::max(a[i][j+1]-a[i][j]+1,0);
j++;
}
else if(std::max(a[i][j+1]-a[i][j]+1,0)>std::max(a[i+1][j]-a[i][j]+1,0))
{
r+=std::max(a[i+1][j]-a[i][j]+1,0);
i++;
}
else if(a[i][j+1]>a[i+1][j])
{
r+=std::max(a[i][j+1]-a[i][j]+1,0);
j++;
}
else
{
r+=std::max(a[i+1][j]-a[i][j]+1,0);
i++;
}
}
}
printf("%d",r);
}
