import java.util.*;

public class Main {
    public static void main(String[] args) {
        Scanner sc = new Scanner(System.in);
        int N = Integer.parseInt( sc.nextLine() );
        int [] count = new int [N];
        for(int i=0; i<N; i++){
            String tem = sc.nextLine();
            String [] arr = tem.split(" ");
            for(int j=0; j<N; j++){
                if( "nyanpass".equals(arr[j]) ){
                    count[j]++;
                }
            }
        }
        int f = 0;
        for(int i=0; i<N; i++){
            if(count[i]==N-1){
                f++;
            }
        }
        if(f!=1){
            System.out.println(-1);
        }else{
            for(int i=0; i<N; i++){
                if(count[i]==N-1){
                    System.out.println(i+1);
                    break;
                }
            }
        }
    }
}