#include<iostream>
#include<vector>
#include<algorithm>
#include<deque>
using namespace std;
using ll=long long;
#define rep(i,n) for(int i=0;i<n;i++)
#define rrep(i,n) for(int i=(n)-1;i>=0;i--)
#define all(v) v.begin(),v.end()
#define rall(v) v.rbegin(),v.rend()
template<class T> bool chmax(T &a, T b){if (a < b){a = b;return true;} else return false;}
template<class T> bool chmin(T &a, T b){if (a > b){a = b;return true;} else return false;}

int main(){
    ios::sync_with_stdio(false);
    std::cin.tie(nullptr);
    int n;
    cin>>n;
    vector<ll>A(n),B(n);
    deque<int>dq;
    rep(i,n){
        cin>>A[i]>>B[i];
    }
    ll as=0,bs=0;
    rrep(i,n){
        if(dq.empty())dq.push_back(i);
        else{
            int f=dq.front(),b=dq.back();
            if(as*B[i]>=bs*A[i])dq.push_front(i);
            else dq.push_back(i);
        }
        as+=A[i];
        bs+=B[i];
    }
    ll ans=0;
    vector<ll>S(n+1);
    rep(i,n)S[i+1]=S[i]+B[dq[i]];
    rrep(i,n)ans+=A[dq[i]]*S[i];
    cout<<ans<<"\n";
}