#include<bits/stdc++.h> using namespace std; int main() { int n; cin>>n; int a[n][2]; for(int i=0;i<n;i++){ cin>>a[i][0]>>a[i][1]; } int sum=a[0][0]; int minn=a[0][0]+a[0][1]; for(int i=1;i<n;i++){ int num=minn; minn=min(minn,a[i][0]); if(minn==num) sum+=minn; else { minn+=a[i][1]; sum+=minn; } } cout<<sum; return 0; }