import java.util.ArrayList;
import java.util.Arrays;
import java.util.Scanner;
public class Main {
	public static void main(String[] ags) {
		Scanner sc = new Scanner(System.in);
		ArrayList<String> list = new ArrayList<>
		(Arrays.asList("a","b","c","d","e","f","g"
				,"h","i","j","k","l","m","n","o","p","q","r","s","t","u","v","w","x","y","z"));
		String str = sc.next();
		int n = list.indexOf(str);
		System.out.println(list.get(n+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