#include <iostream>
#include <algorithm>
#include <vector>
using namespace std;
#define int long long
typedef struct angry {
    int a, b;
} Angry;
vector<Angry> p;
Angry temp;
bool cmp(Angry m, Angry n) { return m.a > n.a; }
signed main() {
    long long int n, sum = 0, t = 0;
    cin >> n;
    for (int i = 0; i < n; i++) {
        cin >> temp.a >> temp.b;
        p.push_back(temp);
    }
    sort(p.begin(), p.end(), cmp);

    for (int i = 0; i < n; i++) {
        if (p[i].a == p[i + 1].a) {
            if (p[i].b > p[i + 1].b) {
                temp = p[i + 1];
                p[i + 1] = p[i];
                p[i] = temp;
            }
        }
        t += p[i].b;
        sum += p[i].a * t;
    }
    cout << sum;
    return 0;
}

/sandbox/1/a.cpp: In function 'int main()':
/sandbox/1/a.cpp:5:13: error: 'long long long' is too long for GCC
    5 | #define int long long
      |             ^~~~
/sandbox/1/a.cpp:13:15: note: in expansion of macro 'int'
   13 |     long long int n, sum = 0, t = 0;
      |               ^~~
/sandbox/1/a.cpp:5:18: error: 'long long long' is too long for GCC
    5 | #define int long long
      |                  ^~~~
/sandbox/1/a.cpp:13:15: note: in expansion of macro 'int'
   13 |     long long int n, sum = 0, t = 0;
      |               ^~~