#pragma GCC optimize("Ofast","unroll-loops","omit-frame-pointer","inline")
#pragma GCC option("arch=native","tune=native","no-zero-upper")
#pragma GCC target("sse,sse2,sse3,ssse3,sse4,popcnt,abm,mmx,avx,avx2")
#pragma GCC optimize(3)
#include<bits/stdc++.h>
#define N 100010
#define rep(i,l,r) for(int i=l;i<=r;i++)
#define drep(i,r,l) for(int i=r;i>=l;i--)
using namespace std;
int rd() {
	int res=0,f=1;char ch=getchar();
	while(ch<'0'||ch>'9') {if(ch=='-') f*=-1;ch=getchar();}
	while(ch>='0'&&ch<='9') res=(res<<1)+(res<<3)+(ch^48),ch=getchar();
	return res*f;
}
int n,m,a[N],tim[N],val[N];
bool dp[(1<<16)+5],f[(1<<16)+5],vis[(1<<16)+5];
int sum[(1<<16)+5];
int st[N],top;
bool cmp(int x,int y) {
	return x>y;
}
void DP(int i,int all) {
	memset(vis,0,sizeof(vis));
	memset(dp,0,sizeof(dp));
	dp[0]=1;
	rep(j,1,all) {
		drep(S,(1<<m)-1,0) if(dp[S]&&!vis[S]) {
			vis[S]=1;
			int S_=((1<<m)-1)^S;
			for(int s=S_;s;s=(s-1)&(S_)) {
				if(sum[s]<=st[j]) dp[S|s]=1;
			}
		}
	}
	drep(S,(1<<m)-1,0) if(f[S]) {
		int S_=((1<<m)-1)^S;
		for(int s=S_;s;s=(s-1)&(S_)) if(dp[s]) {
			f[S|s]=1;
		}
	}
}
int main() {
	n=rd(),m=rd();
	rep(i,1,n) a[i]=rd();
	rep(i,1,m) tim[i]=rd(),val[i]=rd();
	rep(S,0,(1<<m)+5) rep(i,1,m) sum[S]+=(S>>(i-1)&1)*tim[i];
	f[0]=1;
	rep(i,1,m) {
		top=0;
		for(int j=1,k;j<=n;j=k+1) {
			k=j;
			if(a[j]<i) continue;
			while(k<n&&a[k+1]>=i) k++;
			st[++top]=k-j+1;
		}
		sort(st+1,st+top+1,cmp);
		DP(i,min(top,m));
	}
	int ans=0;
	rep(S,0,(1<<16)-1) if(f[S]) {
		int res=0;
		rep(j,1,m) res+=(S>>(j-1)&1)*val[j];
		ans=max(ans,res);
	}
	printf("%d",ans);
	return 0;
}