#include<fstream>
using namespace std;
ifstream f("copii.in");
ofstream g("copii.out");
unsigned int k,n,a[11][11],i,j;
char c;
int main()
{f>>n;
for(i=1;i<=n;i++)for(j=1;j<=n;j++){f>>c;a[i][j]=c-48;}
for(i=1;i<=n;i++)for(j=i;j<=n;j++){a[i][j]=a[i][j]+a[j][i];a[j][i]=a[i][j];}
for(i=1;i<=n;i++)for(j=1;j<=n;j++)if(a[i][j]==0)k++;
g<<k;
f.close();
g.close();
return 0;
}