#include <bits/stdc++.h>
using namespace std;
vector<int> toOrder;
map<int, set<int>> offersByDays;
map<int, set<int>> offers;
int totSum;
int bSearch(int a, int b) {
  if (a == b) {
    return a;
  }
  int curSum = totSum;
  int mid = (a + b) / 2;
  int money = 0;
  for (int i = 0; i <= mid; i++) {
    money++;
    if (offersByDays.count(i) == 0) {
      continue;
    }
    for (auto offer : offersByDays[i]) {
      if (money == 0) {
        break;
      }
      set<int>::iterator itr = offers[offer].lower_bound(mid);
      if (itr != offers[offer].end() && *itr == mid) {
        if (i != mid) {
          continue;
        }
      } else {
        itr = prev(itr);
        if (i != *itr) {
          continue;
        }
      }
      if (money >= toOrder[offer]) {
        money -= toOrder[offer];
        curSum -= toOrder[offer];
      } else {
        curSum -= money;
        money = 0;
      }
    }
  }
  if (money >= 2 * curSum) {
    return bSearch(a, mid);
  }
  return bSearch(mid + 1, b);
}
int main() {
  int n, m;
  cin >> n >> m;
  totSum = 0;
  for (int i = 0; i < n; i++) {
    int temp;
    cin >> temp;
    toOrder.push_back(temp);
    totSum += temp;
  }
  for (int i = 0; i < m; i++) {
    int a, b;
    cin >> a >> b;
    a--;
    b--;
    if (offersByDays.count(a) == 0) {
      offersByDays.insert({a, {b}});
    } else {
      offersByDays[a].insert(b);
    }
    if (offers.count(b) == 0) {
      offers.insert({b, {a}});
    } else {
      offers[b].insert(a);
    }
  }
  cout << bSearch(0, int(4e5)) + 1 << endl;
}
