#include<bits/stdc++.h>
using namespace std;
#define ll long long
#define N 1000000000
inline ll read(){
	ll x=0,f=1;
	char c=getchar();
	while(c<'0'||c>'9'){
		if(c=='-')f=-1;
		c=getchar();
	}
	while(c>='0'&&c<='9'){
		x=x*10+c-'0';
		c=getchar();
	}
	return x*f;
}
ll n,m;
ll val[310],a[310],b[310],dp[310]; 
int main(){
	freopen("snowboots_silver_18feb.in","r",stdin);
	freopen("snowboots_silver_18feb.out","w",stdout);
	n=read(),m=read();
	for(int i=1;i<=n;i++){
		val[i]=read();
		dp[i]=N;
	}
	dp[1]=1;
	for(int i=1;i<=m;i++){
		b[i]=read(),a[i]=read();
	}
	for(int i=1;i<=n;i++){
		if(dp[i]==N)continue;
//		cout<<i<<" dp:"<<dp[i]<<endl;
		for(int j=dp[i];j<=m;j++){
			if(b[j]>=val[i]){
				for(int v=i+1;v<=i+a[j];v++){
					if(b[j]>=val[v]){
						dp[v]=min(dp[v],(ll)j);
//						cout<<i<<" "<<j<<" "<<v<<endl;
					}
				}
			}
		}
	}
	cout<<dp[n]-1;
	return 0;
}