using System;

using System.Collections.Generic;

public class Program

{

    public static bool IsIsomorphic(string s, string t) {

        Dictionary<char,char> map = new();

        HashSet<char> image = new();

        for (int i = 0; i < s.Length; ++i) {

            if (map.ContainsKey(s[i])) {

                if (map[s[i]] == t[i]) continue;

                else return false;

            }

            else if (!image.Contains(t[i])) {

                map.Add(s[i], t[i]);

                image.Add(t[i]);

            }

            else

                return false;

        }

        return true;

    }

    public static void Main()

    {

        string s = "paper";

        string t = "title";

        Console.WriteLine(IsIsomorphic(s,t));

    }

}