func_code_string: #include <bits/stdc++.h>   using namespace std;   const long long maxn = 1e6 + 00;   const long long inf = 1e9 + 800;   long long a[maxn];   int main() {     ios_base::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);     long long n, r, sum = 0;     ;     cin >> n >> r;     for (long long i = 0; i < (1 << n); i++) {       cin >> a[i];       sum += a[i];     }     cout << fixed << setprecision(10);     for (long long i = 0; i < r; i++) {       cout << (long double)sum / (1 << n) << endl;       long long p, v;       cin >> p >> v;       sum -= a[p];       a[p] = v;       sum += a[p];     }     cout << (long double)sum / (1 << n) << endl;   }   