import java.util.*;
public class Main{
  public static void main(String[] args){
    Scanner sc = new Scanner(System.in);
    String s = sc.next();
    char [] c = s.toCharArray();
    char c2 ='a';
    char []alphabet = new char[26];
    for (int i = 0; i < 26; i++){
        alphabet[i] = c2++;
    }
    for(int i=0;i<26;i++){
      if(c[0]==(alphabet[i])){
        System.out.println(alphabet[i+1]);
        return;
      }
    }
         
  }
  

  
}
/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