import java.util.Arrays;
import java.util.*;
public class Main{
  public static void main(String args[]){
    Scanner sc = new Scanner(System.in);
      String C = sc.next();
      char c = C.charAt(0);
      int i = 0;
      char[] alpha = { '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' };
      while(true){
        if(alpha[i]==c){
          System.out.println(alpha[i+1]);
          break;
        }else{
          i++;
        }
      }
  }
}

/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