/*#include<bits/stdc++.h>
using namespace std;
const int maxn=101;
int t,n,ans=0;
struct node
{
	int time;
	int money;
}a[maxn];
void dfs(int num,int time,int rich)
{
	if(num>n||time<a[num].time)
	{
		if(rich>ans) ans=rich;
		return;
	}
	for(int i=num;i<=n;++i)
	{
		if(time>=a[i].time) dfs(i+1,time-a[i].time,rich+a[i].money);
	}
}
int main()
{
	cin>>t>>n;
	for(int i=1;i<=n;++i) cin>>a[i].time>>a[i].money;
	for(int i=1;i<n;++i)
	{
		for(int j=i+1;j<=n;++j)
		{
			if(a[i].time>a[j].time) swap(a[i],a[j]);
		}
	}
	dfs(1,t,0);
	cout<<ans;
	return 0;
}           搜索*/

#include<bits/stdc++.h>;
using namespace std;
int a[100],b[100];
int main()
{
	int t,m,ans=0;
	scanf("%d%d",&t,&m);
	for(int i=0;i<m;++i) scanf("%d%d",&a[i],&b[i]);
	
	for(int s=1;s<(1<<m);++s)
	{
		int sum=0,time=0;
		for(int i=0;i<m;++i)
		{
			if(s&(1<<i))
			{
				time+=a[i];
				sum+=b[i];
			}
		}
		if(time<=t&&ans<sum) ans=sum;
	}
	cout<<ans;
	return 0;
}
//        子集枚举