import java.io.InputStream;
import java.io.IOException;
import java.io.PrintWriter;
import java.util.ArrayDeque;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.BitSet;
import java.util.Comparator;
import java.util.Deque;
import java.util.HashMap;
import java.util.HashSet;
import java.util.InputMismatchException;
import java.util.Map;
import java.util.PriorityQueue;
import java.math.BigDecimal;
import java.math.BigInteger;
    
public class Main{

static final InputStream in=System.in;
static final PrintWriter out=new PrintWriter(System.out);
static final int INF=Integer.MAX_VALUE/2;
static final long LINF=Long.MAX_VALUE/2;
static int T,N;
static int[] c,v;
static int[][] dp;

public static void main(String[] args) throws IOException{
InputReader ir=new InputReader(in);
T=ir.nextInt();
N=ir.nextInt();
c=ir.nextIntArray(N);
v=ir.nextIntArray(N);
dp=new int[N+1][T+1];
for(int i=0;i<N;i++){
Arrays.fill(dp[i],Integer.MIN_VALUE);
dp[i][T]=0;
}
out.println(dfs(0,0));
out.flush();
}

public static int dfs(int a,int t){
if(dp[a][t]>=0) return dp[a][t];
int res=dfs(a+1,t),cnt=0,sum=0;
while(v[a]>0&&t+c[a]*cnt<=T){
sum+=v[a];
res=Math.max(res,dfs(a+1,t+c[a]*cnt)+sum);
v[a]>>=1;
cnt++;
}
return dp[a][t]=res;
}

static class InputReader {
private InputStream in;
private byte[] buffer=new byte[1024];
private int curbuf;
private int lenbuf;

public InputReader(InputStream in) {this.in=in;}
  
public int readByte() {
if(lenbuf==-1) throw new InputMismatchException();
if(curbuf>=lenbuf){
curbuf= 0;
try{
lenbuf=in.read(buffer);
}
catch (IOException e) {
throw new InputMismatchException();
}
if(lenbuf<=0)
return -1;
}
return buffer[curbuf++];
}

public boolean isSpaceChar(int c){return !(c>=33&&c<=126);}

private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;}

public String next() {
int b=skip();
StringBuilder sb=new StringBuilder();
while(!isSpaceChar(b)){
sb.appendCodePoint(b);
b=readByte();
}
return sb.toString();
}
 
public int nextInt() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
int res=0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public long nextLong() {
int c=readByte();
while (isSpaceChar(c)) c=readByte();
boolean minus=false;
if (c=='-') {
minus=true;
c=readByte();
}
long res = 0;
do{
if(c<'0'||c>'9') throw new InputMismatchException();
res=res*10+c-'0';
c=readByte();
}while(!isSpaceChar(c));
return (minus)?-res:res;
}

public double nextDouble(){return Double.parseDouble(next());}

public BigInteger nextBigInteger(){return new BigInteger(next());}

public int[] nextIntArray(int n){
int[] a=new int[n];
for(int i=0;i<n;i++) a[i]=nextInt();
return a;
}
}
}