func_code_string: #include <bits/stdc++.h>   using namespace std;   long long n, k, a, b;   vector<long long> v;   long long rec(long long l, long long r) {     long long i = lower_bound(v.begin(), v.end(), l) - v.begin();     long long j = upper_bound(v.begin(), v.end(), r) - v.begin();     j--;     long long na = j - i + 1;     long long val1 = b * (r - l + 1) * na;     if (na == 0) return a;     if (l == r) {       if (na == 0)         return a;       else         return val1;     }     long long mid = (r + l) / 2;     long long val2 = rec(l, mid) + rec(mid + 1, r);     long long ans = min(val1, val2);     return ans;   }   int main() {     cin >> n >> k >> a >> b;     long long x;     for (long long i = 0; i < k; i++) {       cin >> x;       v.push_back(x);     }     sort(v.begin(), v.end());     long long l = 1, r = pow(2, n);     long long ans = rec(l, r);     cout << ans << endl;   }   