#include <bits/stdc++.h>
#define int long long
using namespace std;
typedef pair<int,int> P;
const int INF = 1e18;
signed main() {
cin.sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
int N, M;
cin >> N >> M;
vector<int> A;
int i, j, a, b;
for(i=0;i<N;i++) {
cin >> a;
A.push_back(a);
}
sort(A.begin(),A.end(),[](int x, int y) {return x > y;});
vector<P> B;
for(i=0;i<M;i++) {
cin >> a >> b;
B.push_back(P(a,b));
}
vector<int> sA;
sA.resize(N+1);
for(i=1;i<=N;i++) {
sA[i] = sA[i-1] + A[i-1];
}
vector<int> C;
C.resize(N+1);
fill(C.begin(),C.end(),INF);
//cout << "C\n";
C[0] = 0;
for(j=0;j<M;j++) {
for(i=N;i>=0;i--) {
int k = min(N,i+B[j].first);
C[k] = min(C[k], C[i] + B[j].second);
}
}
int ans = 0;
for(i=0;i<=N;i++) {
ans = max(ans, sA[i] - C[i]);
}
cout << ans;
}
