import java.util.ArrayList;
import java.util.List;
import java.util.Scanner;

public class Main {

	public static void main(String[] args) {


		Scanner sc = new Scanner(System.in);
		String input = sc.next();
		List<String> alphabetList = new ArrayList<String>();
		alphabetList.add("a");
		alphabetList.add("b");
		alphabetList.add("c");
		alphabetList.add("d");
		alphabetList.add("e");
		alphabetList.add("f");
		alphabetList.add("g");
		alphabetList.add("h");
		alphabetList.add("i");
		alphabetList.add("j");
		alphabetList.add("k");
		alphabetList.add("l");
		alphabetList.add("m");
		alphabetList.add("n");
		alphabetList.add("o");
		alphabetList.add("p");
		alphabetList.add("q");
		alphabetList.add("r");
		alphabetList.add("s");
		alphabetList.add("t");
		alphabetList.add("u");
		alphabetList.add("v");
		alphabetList.add("w");
		alphabetList.add("x");
		alphabetList.add("y");
		alphabetList.add("z");
		int index = alphabetList.indexOf(input);
		System.out.println(alphabetList.get(index + 1));
	}
}

/tmp/hf-datasets-cache/medium/datasets/42704881117311-config-parquet-and-info-qiankunmu-Project_CodeNet-896c9d36/hub/datasets--qiankunmu--Project_CodeNet_Python800_and_Java250/snapshots/c899fde44a77ba1cc14973ed3de064e4ff3aadc7/Project_CodeNet_Java250.tar.gz