func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   const ll INF = 1e14 + 7;   using vi = vector<int>;   using pii = pair<int, int>;   using pli = pair<ll, int>;   int ask(int i, int j) {     cout <<  ?   << i <<     << j << endl;     int ans;     cin >> ans;     return ans;   }   int main() {     int n;     cin >> n;     vi ans(n + 4), curr(n + 4);     curr[0] = ask(1, n);     curr[1] = ask(2, n);     ans[1] = curr[0] - curr[1];     for (int i = 2; i <= n - 1; i++) {       curr[i] = ask(i - 1, i);       ans[i] = curr[i] - ans[i - 1];     }     ans[n] = curr[0];     for (int i = 1; i < n; i++) {       ans[n] -= ans[i];     }     cout <<  ! ;     for (int i = 1; i <= n; i++) {       cout <<     << ans[i];     }     cout << endl;     fflush(stdout);     return 0;   }   