#include<bits/stdc++.h> using namespace std; using ll = long long; template<class T>bool chmax(T &a, const T &b) { if (a<b) { a=b; return 1; } return 0; } template<class T>bool chmin(T &a, const T &b) { if (b<a) { a=b; return 1; } return 0; } #define FOR(i,a,b) for(ll i=(a);i<(b);++i) #define ALL(v) (v).begin(), (v).end() #define p(s) cout<<(s)<<endl #define p2(s, t) cout << (s) << " " << (t) << endl #define br() p("") #define pn(s) cout << (#s) << " " << (s) << endl #define p_yes() p("Yes") #define p_no() p("No") const ll mod = 1e9 + 7; const ll inf = 1e18; void vprint(vector<bool> A){ ll L = A.size(); FOR(i, 0, L){ if(i) cout << ' '; cout << A[i]; } cout << endl; } int main(){ cin.tie(0); ios::sync_with_stdio(false); // input ll N; cin >> N; vector<bool> ren(N, true); FOR(i, 0, N){ FOR(j, 0, N){ string s; cin >> s; if(i==j) continue; if(s!="nyanpass"){ ren[j] = false; } } } ll id = -1; ll count=0; FOR(i, 0, N){ if(ren[i]){ count++; id = i; } } if(count==1){ p(id+1); }else{ p(-1); } return 0; }