#include <stdio.h>
#include <stdlib.h>

int ukloniParneCifreNeparneUmanji(int n){
  if(n < 10){
    return n % 2 == 0 ? 0 : n - 1;
  }
  int jed = n % 10;
  if(jed % 2 == 0){
        return ukloniParneCifreNeparneUmanji(n/10);
  }
  return ukloniParneCifreNeparneUmanji(n/10) * 10 + jed - 1;
}

int main(int argc, char const *argv[]) {
  int n;
  scanf("%d", &n);
  if(n <= 0){
    fprintf(stderr, "-1\n");
    exit(EXIT_FAILURE);
  }

  printf("%d\n", ukloniParneCifreNeparneUmanji(n));
  return 0;
}