func_code_string: #include <bits/stdc++.h>   using namespace std;   struct exam {     long long a;     long long b;   };   exam a[200000];   long long n, r, avg;   bool comp(exam a, exam b) { return a.b < b.b; }   int main() {     cin >> n >> r >> avg;     for (int i = 0; i < n; i++) cin >> a[i].a >> a[i].b;     sort(a, a + n, comp);     long long needed = n * avg;     long long owned = 0;     for (int i = 0; i < n; i++) {       owned += a[i].a;     }     needed -= owned;     long long answer = 0;     int i = 0;     while (needed > 0 && i < n) {       if (r - a[i].a < needed) {         answer += (r - a[i].a) * a[i].b;         needed -= (r - a[i].a);       } else {         answer += (needed)*a[i].b;         needed = 0;       }       i++;     }     cout << answer << endl;   }   