#include <bits/stdc++.h>
using namespace std;
int main() {
// your code goes here
ios::sync_with_stdio(0);
int n;
cin>>n;
int score[n],pos[n];
for (int i = 0; i < n; i++) {
cin>>score[i]>>pos[i];
}
int ans=0;
for(int i=0;i<n;i++){
for(int j=0;j<n;j++){
ans=ans+abs(pos[i]-pos[j])*max(score[i],score[j]);
}
}
cout<<ans;
return 0;
}
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