#include <iostream>
using namespace std;
long long s[25][25];
int n, i, j;
int main(){
    cin>>n;
    for (i=1;i<=n;i++){
        for (j=1;j<=n;j++){
            cin>>s[i][j];
        }
    }
    int sum1=0;
    for (j=1;j<=n;j++){
        i=1;
        while (i<j){
            sum1+=s[i][j];
            i++;
        }
    }
    int sum2=0;
    for (j=1;j<=n;j++){
        i=j+1;
        while (i<=n){
            sum2+=s[i][j];
            i++;
        }
    }
    while (sum2){
        int r=sum1%sum2;
        sum1=sum2;
        sum2=r;
    }
    cout<<sum1;
    return 0;
}
#include <iostream>
using namespace std;
long long s[25][25];
int n, i, j;
int main(){
    cin>>n;
    for (i=1;i<=n;i++){
        for (j=1;j<=n;j++){
            cin>>s[i][j];
        }
    }
    int sum1=0;
    for (j=1;j<=n;j++){
        i=1;
        while (i<j){
            sum1+=s[i][j];
            i++;
        }
    }
    int sum2=0;
    for (j=1;j<=n;j++){
        i=j+1;
        while (i<=n){
            sum2+=s[i][j];
            i++;
        }
    }
    while (sum2){
        int r=sum1%sum2;
        sum1=sum2;
        sum2=r;
    }
    cout<<sum1;
    return 0;
}