#include <iostream>
#include <string>
#include <vector>

template <class T>
std::vector<T> vec(int len, T elem) { return std::vector<T>(len, elem); }

const std::string nyan = "nyanpass";

void solve() {
    int n;
    std::cin >> n;

    auto xss = vec(n, vec(n, std::string()));
    for (auto& xs : xss) {
        for (auto& x : xs) std::cin >> x;
    }

    int ans = -1;
    for (int j = 0; j < n; ++j) {
        bool ok = true;
        for (int i = 0; i < n; ++i) {
            if (i != j && xss[i][j] != nyan) ok = false;
        }
        if (ok) {
            if (ans == -1) {
                ans = j;
            } else {
                std::cout << -1 << std::endl;
                return;
            }
        }
    }

    std::cout << (ans == -1 ? -1 : ans + 1) << std::endl;
}

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

    solve();

    return 0;
}