#include <iostream> #include <algorithm> using namespace std; const int MAXN = 105; int buy[MAXN]; int keep[MAXN]; int main() { int n; cin >> n; for(int i = 1; i <= n; i++) { cin >> buy[i] >> keep[i]; } long long total = 0; int min_cost = buy[1]; total += min_cost; // 第一站必须吃本站买的鱼 for(int i = 2; i <= n; i++) { // 要么继续保存上一轮最便宜的鱼带过来，要么本站新买 min_cost = min( min_cost + keep[i-1], buy[i] ); total += min_cost; } cout << total << endl; return 0; }