#include <bits/stdc++.h> 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 temp = a[0]; int sum = a[0] + b[0]; for(int i = 1;i < n;i++) { if(a[i] < sum) { sum = a[i]; } temp += sum; sum += b[i]; } cout<<temp; return 0; }