#include<bits/stdc++.h>

using namespace std;
using ll=long long;
#define rep2(i, a, n) for(int i = (a); i < (n); i++)
#define rep(i, n) rep2(i,0,n)

int main(){
  cin.tie(nullptr);ios_base::sync_with_stdio(false);

  int n;cin>>n;
  string s[n][n];
  rep(i,n){
    rep(j,n){
      cin>>s[i][j];
    }
  }
  int cnt1,cnt2=0,res=0;
  rep(i,n){
    cnt1=0;
    rep(j,n)if(s[j][i]=="nyanpass")cnt1++;
    if(cnt1==n-1){
      cnt2++;
      if(cnt2==1)res=i;
    }
  }

  //$B$l$s$A$g$s$rFCDj$G$-$?>l9g$O$=$NB<L1HV9f$r!"FCDj=PMh$J$+$C$?>l9g$O(B-1$B$r=PNO$;$h!#(B
  cout<<(cnt2==1?res+1:-1)<<endl;
}