#include <iostream> #include <vector> #include <map> #include <set> #include <queue> #include <string> #include <iomanip> #include <algorithm> #include <cmath> #include <stdio.h> using namespace std; #define int long long int MOD = 1000000007; signed main() { cin.tie(0); ios::sync_with_stdio(false); int N; cin >> N; vector<int> A(N); vector<int> B(N); vector<int> C(N); int res = 0; for (int i = 0; i < N - 1; i++) { cin >> A[i]; } for (int i = 0; i < N; i++) { cin >> B[i] >> C[i]; } int k = 0; for (int i = 0; i < N; i++) { k += -B[i] + C[i]; res += k*A[i]; } cout << res << endl; }