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