#include<bits/stdc++.h>
using namespace std;
int n,a[10000000],b[10000000];
int miq=1e9,mih=1e9;
int main(){
	cin>>n;
	for(int i=1;i<=n;i++){
		cin>>a[i]>>b[i];
		miq=min(b[i],miq);
		mih=min(a[i]-b[i],mih);
	}
	cout<<(mih+miq)*n;
    return 0;
}