#include <bits/stdc++.h>
using namespace std;
int INF = (int)1e9;
long long INFINF = (long long)1e18 + 10;
const long double PI = 3.14159265358979323846;
long long powermodm(long long x, long long n, long long mod) {
  long long result = 1;
  while (n > 0) {
    if (n % 2 == 1) result = (result * x) % mod;
    x = (x * x) % mod;
    n = n / 2;
  }
  return result;
}
long long GCD(long long, long long);
long long LCM(long long, long long);
long long power(int, int);
long long choose(long long, long long);
int ones(long long);
void extendedEuclid(long long, long long);
long long MMI(long long, long long);
void fastscan(int &);
bool checkithbit(long long, long long);
int n, m;
int k[400005], ktemp[400005];
vector<int> day[400005], daytemp[400005];
int checkdays(int days) {
  for (int i = 1; i <= n; i++) {
    ktemp[i] = k[i];
  }
  vector<int> vis(400005);
  for (int i = 0; i <= 200005; i++) {
    daytemp[i].clear();
  }
  for (int i = days; i >= 1; i--) {
    for (auto it : day[i]) {
      if (vis[it] == 1) {
        continue;
      } else {
        vis[it] = 1;
        daytemp[i].push_back(it);
      }
    }
  }
  int balance = 0;
  for (int i = 1; i <= days; i++) {
    balance++;
    if (daytemp[i].size() != 0) {
      for (auto it : daytemp[i]) {
        int x = min(balance, ktemp[it]);
        ktemp[it] -= x;
        balance -= x;
      }
    }
  }
  int countremain = 0;
  for (int i = 1; i <= n; i++) {
    countremain += ktemp[i];
  }
  if (2 * countremain <= balance) {
    return 1;
  } else {
    return 0;
  }
}
int find(int s, int e) {
  int mid, ans;
  while (s <= e) {
    m = (s + e) / 2;
    if (checkdays(m)) {
      ans = m;
      e = m - 1;
    } else {
      s = m + 1;
    }
  }
  return ans;
}
int main() {
  ios_base::sync_with_stdio(0);
  cin.tie(0);
  cout.tie(0);
  cin >> n >> m;
  for (int i = 1; i <= n; i++) {
    cin >> k[i];
  }
  for (int i = 0; i < m; i++) {
    int x, y;
    cin >> x >> y;
    day[x].push_back(y);
  }
  int ans = find(1, 400005);
  cout << ans << endl;
  return 0;
}
bool checkithbit(long long a, long long i) {
  if (a & (1 << i)) {
    return true;
  } else {
    return false;
  }
}
long long GCD(long long a, long long b) {
  if (b == 0)
    return a;
  else
    return GCD(b, a % b);
}
long long LCM(long long a, long long b) {
  return (max(a, b) / GCD(a, b)) * min(a, b);
}
long long power(int a, int n) {
  unsigned long long int result = 1, x = a;
  while (n > 0) {
    if (n % 2 == 1) result = result * x;
    x = x * x;
    n = n / 2;
  }
  return result;
}
long long choose(long long n, long long k) {
  if (k == 0) return 1;
  return (n * choose(n - 1, k - 1)) / k;
}
int ones(long long n) {
  int c = 0;
  while (n) {
    n = n & (n - 1);
    c++;
  }
  return c;
}
long long d, x, y;
void extendedEuclid(long long A, long long B) {
  if (B == 0) {
    d = A;
    x = 1;
    y = 0;
  } else {
    extendedEuclid(B, A % B);
    int temp = x;
    x = y;
    y = temp - (A / B) * y;
  }
}
long long MMI(long long a, long long p) {
  extendedEuclid(a, p);
  if (d == 1 && p != 1)
    return ((x % p) + p) % p;
  else
    return -1;
}
void fastscan(int &number) {
  bool negative = false;
  register int c;
  number = 0;
  c = getchar();
  if (c == '-') {
    negative = true;
    c = getchar();
  }
  for (; (c > 47 && c < 58); c = getchar()) number = number * 10 + c - 48;
  if (negative) number *= -1;
}
