func_code_string: #include <bits/stdc++.h>   using namespace std;   const int N = 1e5 + 7;   pair<long long, long long> a[N];   long long top, k, n, avr, mx;   int main() {     scanf( %d %d %d , &n, &mx, &avr);     for (int i = 1; i <= n; i++) {       int b, r;       scanf( %d %d , &b, &r);       a[i] = make_pair(r, b);       top += b;     }     sort(a + 1, a + 1 + n);     long long tmp = 0, i = 1;     while (top < avr * n) {       long long t = min(avr * n - top, mx - a[i].second);       top += t;       tmp += t * a[i].first;       i++;     }     cout << tmp << endl;     return 0;   }   