import java.util.Scanner;
public class No239 {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		int n = sc.nextInt();
		boolean notNyanpass[] = new boolean[n];
		for(int i = 0; i < n; i++){
			for(int j = 0; j < n; j++){
				String aisatu = sc.next();
				if(!(aisatu.equals("-")) && !(aisatu.equals("nyanpass"))){
					notNyanpass[j] = true;
				}
			}
		}
		sc.close();
		int renchonCount = 0;
		int renchon = 0;
		for(int i = 0; i < n; i++){
			if(notNyanpass[i] == false){
				renchonCount++;
				renchon = i + 1;
			}
		}
		if(renchonCount == 1){
			System.out.println(renchon);
		}else{
			System.out.println(-1);			
		}
	}
}