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

void main(void) {
char pw[129];
memset(pw, '\0', sizeof(pw));
int d, dd, ptr;

dd = 999;
ptr = 0;

pw[ptr] = 'a';
  while(1) {
    printf("? %s\n", pw);
    scanf("%d", &d);
    if(d == 0) {
      break;
    }
    if(dd > d) {
      dd = d;
      ptr++;
      pw[ptr] = 'a';
    }
    pw[ptr]++;
  }
  printf("! %s\n", pw);
}