#include <bits/stdc++.h>
#include <experimental/random>
#include <random>
//#include <ext/pb_ds/assoc_container.hpp>
//using namespace __gnu_pbds;
using namespace std;
using ld = long double;
using ll = long long;
const ll INF = 3e18, MOD = 1e9 + 7;
void solve();
signed main() {
#ifdef LOCAL
freopen("input.txt", "r", stdin);
freopen("output.txt", "w", stdout);
#endif
ios::sync_with_stdio(false);
cin.tie(0);
int q = 1;
//cin >> q;
while (q--) {
solve();
}
}
void solve() {
ll m, n; cin >> m >> n;
vector<ll> a(m);
for (int i = 0; i < m; i++) {
cin >> a[i];
}
sort(a.rbegin(), a.rend());
vector<pair<ll, ll>> b;
for (int i = 0; i < n; i++) {
ll c, e; cin >> c >> e;
b.emplace_back(c, e);
}
vector<ll> dp(m + 1, INF);
dp[0] = 0;
for (auto [c, e] : b) {
vector<ll> ndp(m + 1, INF);
for (int j = 0; j <= m; j++) {
ndp[j] = min(dp[j], ndp[j]);
ndp[min(m, j + c)] = min(ndp[min(m, j + c)], dp[j] + e);
}
dp = ndp;
}
ll ans = -INF;
for (ll i = m - 1; i >= 0; i--) {
dp[i] = min(dp[i], dp[i + 1]);
}
ll sm = 0;
for (int i = 0; i < m; i++) {
sm += a[i];
ans = max(ans, sm - dp[i + 1]);
}
cout << max(0ll, ans);
}
