#include <bits/stdc++.h>
using namespace std;
int main() {
  int n;
  cin >> n;
  int sum = 0, a;
  for (int i = 0; i < n; i++) {
    cin >> a;
    sum += a;
  }
  int m;
  cin >> m;
  vector<char> good(1e5 + 1, false);
  int l, r;
  for (int i = 0; i < m; i++) {
    cin >> l >> r;
    for (int j = l; j <= r; j++) {
      good[j] = true;
    }
  }
  for (int i = sum; i <= 1e5; i++) {
    if (good[i]) {
      cout << i << endl;
      return 0;
    }
  }
  cout << -1 << endl;
  return 0;
}
