import java.util.*;
 
class Main {
	public static void main(String[] args) {
		Scanner sc = new Scanner(System.in);
		String a = sc.next();
		char[] b = a.toCharArray();
		char []alphabet = new char[26];
	    char c = 'a';
	    for (int i = 0; i < 26; i++){
	        alphabet[i] = c++;
	    }
	    
	    for (int i = 0; i < 26; i++){
	        if(b[0] == alphabet[i]) {
	        	System.out.println(alphabet[i+1]);
	        }
	    }


 
		sc.close();
	}
}
/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