#include <stdio.h>
#include <string.h>

//beecrowd | 2138
// https://www.beecrowd.com.br/repository/UOJ_2138_en.html

int main() {
  int v = 0;
  int ans = 0;
  int db[10] = {0};
  char n[100];

  scanf("%s", n);

  for (int i = 0; i < strlen(n); i++) {
    db[n[i]-48] += 1;
    if (db[n[i]-48] > v){
      v = db[n[i]-48];
    }
  }
  for (int i = 9; i >= 0; i--) {
    if (db[i] == v){
      printf("%d\n", i);
      break;
    }
  }
  return 0;
}

// Wrong answer (100%) 
// Language:
//     C99 (gcc 4.8.5, -std=c99 -O2 -lm) [+0s] 
// Runtime:
//     0.000s
// File size:
//     398 Bytes