#include <bits/stdc++.h>
using namespace std;
#define int long long
const int M=505;
int n,m,c[M],e[M],ans;
vector <int> box;
priority_queue <int> pq;
bool cmp(int idx1,int idx2){
int sum1=e[idx1]*c[idx2],sum2=e[idx2]*c[idx1];
if(sum1!=sum2) return sum1<sum2;
else return c[idx1]<c[idx2];
}
signed main()
{
ios::sync_with_stdio(0);
cin.tie(0);
cin >> n >> m;
for(int i=1;i<=n;i++){
int x;
cin >> x;
pq.push(x);
}
for(int i=1;i<=m;i++){
box.push_back(i);
cin >> c[i] >> e[i];
}
sort(box.begin(),box.end(),cmp);
for(int idx:box){
int sum=0;
for(int i=0;i<c[idx] && pq.size();i++){
sum+=pq.top();
pq.pop();
}
if(sum>e[idx]) ans+=sum-e[idx];
if(pq.empty() || sum<e[idx]) break;
}
cout << ans;
}
