idx = 1;

cin>>n>>m;

int tc, td;

cin>>tc>>td;

for(int i=0; i<n/tc; i++){

earn[idx] = td;

cost[idx] = tc;

idx++;

}

//cin>>cost[0]>>earn[0];

//idx++;

for(int i=0; i<m; i++){

int a,b,c,d;

cin>>a>>b>>c>>d;

int number = a/b;;

//cout<<"build "<<c<<" "<<d<<" num = "<<number<<endl;

for(int k=0; k<number; k++){

cost[idx] = c;

earn[idx] = d;

idx++;

}

}

memset(dp,0,sizeof(dp));

//cout<<"earn 0 = "<<earn[0]<<endl;

//dp[0][cost[0]] = earn[0];

int ans = 0;

for(int i=1; i<=idx; i++){

for(int j=0; j<=n; j++){

dp[i][j] = max(dp[i][j], dp[i-1][j]);

if(j-cost[i]>=0){

dp[i][j] = max(dp[i][j], earn[i] + dp[i-1][j-cost[i]]);

//cout<<"dp["<<i<<"]["<<j<<"] = "<<dp[i][j]<<endl;

ans = max(ans, dp[i][j]);

}

}

}

cout<<ans<<endl;