#include <cstdio>
#include <stdio.h>
#include <stdbool.h>
#include <iostream>
#include <map>
#include <vector>
#include <climits>
#include <stack>
#include <string>
#include <queue>
#include <algorithm>
#include <set>
#include <unordered_set>
#include <unordered_map>
#include <cmath>
#include <cctype>
#include <bitset>
#include <iomanip>
#include <cstring>
#include <numeric>
#include <cassert>
#include <chrono>
using namespace std;
#define int long long
#define pii pair<int, int>
#define mp make_pair
#define pb push_back
#define fi first
#define se second
int32_t main(){
ios_base::sync_with_stdio(0);
cin.tie(0);
cout.tie(0);
int k, n, ans=0;
cin>>k>>n;
vector<int> val(k), dp(k+1, LLONG_MAX/2);
vector<pii> vect(n);
for (int i=0; i<k; ++i)cin>>val[i];
for (int i=0; i<n; ++i)cin>>vect[i].se>>vect[i].fi;
sort(val.begin(), val.end(), greater<int>());
dp[0]=0;
for (int i=0; i<n; ++i)for (int j=k-1; j>=0; --j)dp[min(k, j+vect[i].se)]=min(dp[min(k, j+vect[i].se)], dp[j]+vect[i].fi);
for (int i=0, sum=0; i<k; ++i)sum+=val[i], ans=max(ans, sum-dp[i+1]);
cout<<ans;
}
