#include <bits/stdc++.h>
using namespace std;
const long long MOD = (long long)1e9 + 7;
const long double PI = 3.141592653589793238462643383279502884197;
long long gcd(long long a, long long b) { return b ? gcd(b, a % b) : a; }
long long mp(long long a, long long b) {
  long long ret = 1;
  while (b) {
    if (b & 1) ret = ret * a % MOD;
    a = a * a % MOD;
    b >>= 1;
  }
  return ret;
}
priority_queue<int, vector<int>, greater<int>> pq;
vector<int> v;
char ans[101];
int main() {
  int n;
  scanf("%d", &n);
  if (n <= 3) {
    printf("? 1 1\n");
    fflush(stdout);
    char t;
    scanf(" %c", &t);
    ans[0] = t;
    if (n >= 2) {
      printf("? 2 2\n");
      fflush(stdout);
      scanf(" %c", &t);
      ans[1] = t;
    }
    if (n == 3) {
      printf("? 3 3\n");
      fflush(stdout);
      scanf(" %c", &t);
      ans[2] = t;
    }
    printf("! %s", ans);
    fflush(stdout);
    return 0;
  }
  int nn = n / 2;
  printf("? 1 %d\n", nn);
  printf("? 2 %d\n", nn);
  fflush(stdout);
  int d[101] = {0};
  for (int i = 0; i < (nn + 1) * nn / 2; i++) {
    string t;
    cin >> t;
    for (char c : t) d[(int)(t).size()] += c;
  }
  for (int i = 0; i < (nn - 1) * nn / 2; i++) {
    string t;
    cin >> t;
    for (char c : t) d[(int)(t).size()] -= c;
  }
  for (int i = nn; i >= 1; i--) d[i] -= d[i - 1];
  for (int i = 1; i <= nn; i++) ans[i - 1] = d[i];
  printf("? 1 %d\n", n);
  fflush(stdout);
  memset(d, 0, sizeof(d));
  for (int i = 0; i < n * (n + 1) / 2; i++) {
    string t;
    cin >> t;
    for (char c : t) d[(int)(t).size()] += c;
  }
  if (n % 2) ans[nn] = d[nn + 1] - d[nn];
  ans[n - 1] = d[n] - (d[2] - d[1]) - ans[0];
  for (int i = 1; i < nn; i++) {
    int tt = (d[i + 1] - d[i]) - (d[i + 2] - d[i + 1]);
    ans[n - i - 1] = tt - ans[i];
  }
  printf("! %s\n", ans);
  fflush(stdout);
}
