#include <iostream> #include <vector> #include <algorithm> using namespace std; int main() { int n; cin >> n; vector<int> fish(n), save(n); for (int i = 0; i < n; ++i) { cin >> fish[i] >> save[i]; } int total = 0; int current_min = fish[0]; total += current_min; for (int i = 1; i < n; ++i) { current_min += save[i-1]; current_min = min(current_min, fish[i]); total += current_min; } cout << total << endl; return 0; }