#include<iostream>#include<cstdio>using namespace std;int f[10001];int main(){int n,t,w[5001],v[5001],i,j;scanf("%d %d",&t,&n);for (i=1;i<=n;i++)scanf("%d %d",&w[i],&v[i]);for (i=1;i<=n;i++)for (j=t;j>=w[i];j--)f[j]=max(f[j],f[j-w[i]]+v[i]);printf("%d",f[t]);return 0;}