#include<bits/stdc++.h> using namespace std; int m,n; int f[1001][1001]; int w[10005]; int c[10005]; int main(){ cin>>m>>n; for(int i=1;i<=n;i++)scanf("%d %d",&w[i],&c[i]); for(int i=1;i<=n;i++){ for(int j=1;j<=m;j++){ if(j>=w[i]) f[i][j]=max(f[i-1][j],f[i-1][j-w[i]]+c[i]); else f[i][j]=f[i-1][j]; } } cout<<f[n][m]<<endl; }