func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   using ld = long double;   using pii = pair<int, int>;   using cd = complex<ld>;   int query(int l, int r) {     cout <<  ?   << l <<     << r << endl;     cin >> l;     return l;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(nullptr);     int n;     cin >> n;     vector<int> sums;     for (int i = 1; i < n; i++) {       sums.push_back(query(i, i + 1));     }     int sum123 = query(1, 3);     vector<int> a(n);     int a2 = sums[0] + sums[1] - sum123;     a[0] = sums[0] - a2;     a[1] = a2;     for (int i = 2; i < n; i++) {       a[i] = sums[i - 1] - a[i - 1];     }     cout <<  !  ;     for (int x : a) {       cout << x <<    ;     }     cout << endl;     return 0;   }   