function Main(input) {
	var str0 = input.charAt(0);
  	var str1 = input.charAt(1);
  	var str2 = input.charAt(2);
  	var str3 = input.charAt(3);
  	if (str0 == str1 && str2 == str3) {
          console.log("Yes");
    } else if (str0 == str2 && str1 == str3){
          console.log("Yes");
   	} else if (str0 == str3 && str1 == str2){
	  console.log("Yes");
    } else {
      console.log("No");
    }
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));