#include <iostream>
#include <cstring>

using namespace std;

int main(int argc, const char * argv[])
{
    int n;
    cin>>n;
    bool mat[n][n];
    memset(mat,false,sizeof(mat));
    for(int ctr1=0;ctr1<n;ctr1++){
        for(int ctr2=0;ctr2<n;ctr2++){
        string t;
        cin>>t;
        if(t=="-" || t=="nyanpass")
            mat[ctr1][ctr2]=true;
        }
    }
    int rez=-1;
    for(int ctr1=0;ctr1<n;ctr1++){
        bool npass=true;
        for(int ctr2=0;ctr2<n;ctr2++){
            if (mat[ctr2][ctr1]==false)
                npass=false;
        }
        if(npass){
            if(rez!=-1){
                rez=-1;
                break;
            }
            else {
                rez=ctr1+1;
            }
        }
    }
    cout<<rez;
    return 0;
}