# include<stdio.h> # include<iostream> # include<string> using namespace std; int main(){ int n; cin>>n; int a[n],b[n]; for(int i=0;i<n;i++){ cin>>a[i]>>b[i]; } int min=99999,t=0; for(int i=0;i<n;i++){ if(min>a[i]){ min=a[i]; } t=t+min; min=min+b[i]; } cout<<t; return 0; }