#include<bits/stdc++.h> using namespace std; long long s1[10005],s2[10005]; int main() { long long n,a,b,sum=0,min=10000; cin>>n; for(int i=1;i<=n;i++) { cin>>s1[i]>>s2[i]; sum+=s1[i]; if(s2[i]<min) min=s2[i]; } cout<<sum*min; return 0; }