#include <bits/stdc++.h>
using namespace std;
#pragma GCC diagnostic ignored "-Wmissing-declarations"
inline int safe_mul(const int x, const int y)
    __attribute__((warn_unused_result));
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  int n, m;
  cin >> n >> m;
  vector<int> a(n);
  for (int& x : a) cin >> x;
  int const inf = 200001;
  vector<vector<int>> te(inf + 2);
  for (int i = 0; i < m; ++i) {
    int d, t;
    cin >> d >> t;
    te[d].push_back(t - 1);
  }
  int l = 0;
  int r = inf;
  while (r - l > 1) {
    int mid = (l + r) >> 1;
    auto tmpa = a;
    int val = mid;
    int sum = 0;
    for (int i = mid; i >= 1; --i) {
      for (int x : te[i]) {
        int cur = min(val, i);
        int need = min(tmpa[x], cur);
        cur -= need;
        val = min(val, cur);
        tmpa[x] -= need;
        sum += need;
      }
    }
    if (accumulate(begin(tmpa), end(tmpa), 0LL) * 2 <= mid - sum)
      r = mid;
    else
      l = mid;
  }
  if (r == inf) {
    int mid = inf - 1;
    auto tmpa = a;
    int val = mid;
    int64_t sum = 0;
    for (int i = mid; i >= 1; --i) {
      for (int x : te[i]) {
        int cur = min(val, i);
        int need = min(tmpa[x], cur);
        cur -= need;
        val = min(val, cur);
        tmpa[x] -= need;
        sum += need;
      }
    }
    sum += accumulate(begin(tmpa), end(tmpa), 0LL) * 2;
    cout << sum << endl;
  } else {
    cout << r << endl;
  }
}
