import java.io.BufferedReader;
import java.io.InputStreamReader;

public class No239 {
    public static void main(String[] args) {
        try {
            BufferedReader br = new BufferedReader(new InputStreamReader(
                    System.in));
            int N = Integer.parseInt(br.readLine());
            String[][] a = new String[N][N];
            for (int i = 0; i < N; i++) {
                a[i] = br.readLine().split(" ");
            }

            // にゃんパスカウンター
            int count[] = new int[N];

            for (int i = 0; i < N; i++) {
                for (int j = 0; j < N; j++) {
                    if (a[i][j].equals("nyanpass")) {
                        count[j]++;
                    }
                }
            }

            int num = -1;
            for (int i = 0; i < N; i++) {
                if (count[i] == N - 1) {
                    if (num == -1) {
                        num = i + 1;
                    } else {
                        num = -1;
                        break;
                    }
                }
            }

            System.out.println(num);

        } catch (Exception e) {
            e.printStackTrace();
            System.err.println("Error:" + e.getMessage());
        }
    }

}