#include "bits/stdc++.h"
using namespace std;
typedef long long ll;
typedef pair<int, int> pii;
typedef pair<ll, ll> pll;
#define INF 1<<30
#define LINF 1LL<<60

/*
 <url:https://joi2014ho.contest.atcoder.jp/img/other/joi2014ho/joi2014ho2.pdf>
 ?????????============================================================
 
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 =================================================================
 ?§£??¬=============================================================
 
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 dp[i][j] := i???????????±?????§????????¨??????j???????\?????????\?????????????°??????±????????????
 ????±???????
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 ================================================================
 */
int main(void) {
    cin.tie(0); ios::sync_with_stdio(false);
    ll M,N; cin >> M >> N;
    vector<ll> P(M);
    vector<ll> C(N),E(N);
    
    for(int i = 0; i < M;i++)cin >> P[i];
    for(int j = 0; j < N;j++)cin >> C[j] >> E[j];
    
    sort(P.begin(),P.end());
    reverse(P.begin(),P.end());
    
    vector<vector<ll>> dp(N+1,vector<ll>(M+1,LINF));
    dp[0][0] = 0; dp[1][0] = 0;
    for(int j = 1; j <= min(M,C[0]);j++) dp[1][j] = E[0];
    for(int i = 1; i < N;i++){
        for(int j = 0; j <= M;j++){
            dp[i+1][j] = min(dp[i+1][j],dp[i][j]);
            dp[i+1][min(M,j+C[i])] = min(dp[i+1][min(M,j+C[i])],dp[i][j] + E[i]);
        }
    }
    
    ll res = 0;
    vector<ll> cusum(M+1,0);
    for(int i = 0; i < M;i++)cusum[i+1] = cusum[i] + P[i];

    for(int i = 0; i <=M;i++){
        res = max(res,cusum[i] - dp[N][i]);
    }
    cout << res << endl;
    return 0;
}

Measured memory_bytes: 42212