#include <stdio.h>
#define SIZE 5

int main(void) {
  char v[SIZE] = "abcde";
  char c;
  char res;

  scanf("%c", &c);

  for(int i = 0; i < SIZE - 1; i++) {
    if(v[i] < c && c < v[i+1]) {
      res = v[i+1];
      v[i+1] = c;
      SIZE++;
      for(j = i+1; j < SIZE + 1; j++) {
    v[j] = res;
    res = v[j+1];
      }
    }
  }
}