func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 1e5 + 1e1;   long long n;   long long r, avg;   long long must, ans = 0, sum = 0;   pair<long long, long long> d[MAXN];   int main() {     cin >> n >> r >> avg;     long long x, y;     for (long long i = 1; i <= n; i++) {       scanf( %I64d%I64d , &x, &y);       sum += x;       d[i] = make_pair(y, x);     }     must = max(n * avg - sum, 1LL * 0);     sort(d + 1, d + n + 1);     long long i = 1;     while (must) {       ans += min(must, r - d[i].second) * d[i].first;       must -= min(must, r - d[i].second);       i++;     }     cout << ans;   }   