#include<bits/stdc++.h> using namespace std; int main(){ int n,yu[101],you[101],sum=0,min=32767; cin>>n; for(int i=0;i<n;i++){ cin>>yu[i]>>you[i]; } for(int i=0;i<n;i++){ if(yu[i]<min)min=yu[i]; sum+=min; min+=you[i]; } cout<<sum; return 0; }