#include<iostream> #include<algorithm> using namespace std; struct vegetable { int ve; int mon; int buy; }; int main() { int n,sum=0;; cin>>n; struct vegetable a[n]; for(int i=0;i<n;i++) { cin>>a[i].ve>>a[i].mon; a[i].buy=0; } for(int l=1;l<=100;l++) { for(int i=0;i<n;i++) { if(a[i].buy==1) { break; } if(a[i].mon==l) { for(int j=i;j<n;j++) { if(a[j].buy==1) { break; } sum+=a[j].ve*l; a[j].buy=1; } break; } } } cout<<sum; return 0; }