func_code_string: #include <bits/stdc++.h>   using namespace std;   using ll = long long;   const ll llinf = (1ll << 61) - 1;   const int inf = 1000000007;   int TC = 1, CN, n, r, c[1 << 18 | 5];   signed main() {     cin.tie(0)->sync_with_stdio(0);     cin.exceptions(cin.failbit);     cout.precision(11), cout.setf(ios::fixed);     auto kase = [&]() -> void {       cin >> n >> r;       double sum = 0;       for (int i = 0; i < 1 << n; i++) {         cin >> c[i], sum += c[i];       }       for (int i = 0; i < r; i++) {         cout << sum / (1 << n) <<   n ;         int z, g;         cin >> z >> g;         sum -= c[z], c[z] = g, sum += c[z];       }       cout << sum / (1 << n) <<   n ;     };     while (CN++ != TC) kase();   }   