#include <iostream>
#include <algorithm>
using namespace std;
int main(){
  int T,N;
  cin>>T;
  cin>>N;
  int ary1[N];
  for(int i=0;i<N;++i){
    cin>>ary1[i];
  }
  int ary2[N];
  for(int i=0;i<N;++i){
    cin>>ary2[i];
  }
  int ary3[N][10];
  for(int i=0;i<N;++i){
    ary3[i][0]=ary2[i];
  }
  for(int i=0;i<N;++i){
    for(int j=1;j<10;++j){
      if(ary3[i][j-1]!=0) ary3[i][j]=(ary3[i][j-1]/2);
      else ary3[i][j]=0;
    }
  }
  int ary4[N];
  for(int i=0;i<N;++i){
    ary4[i]=0;
  }
  int ans1=0,ans2=0;
  while(1){
    double a=0;
    int b=0;
    for(int i=0;i<N;++i){
      double d=((double)(ary3[i][ary4[i]])/(double)(ary1[i]));
      if(a<d && T>=ary1[i]){
        a=d;
        b=i;
      }
      int e=ary3[i][ary4[i]];
      if(T>=ary1[i] && ans2<ans1+e) ans2=ans1+e;
    }
    if(a==0) break;
    int c=ary3[b][ary4[b]];
    ans1+=c;
    ary4[b]+=1;
    T-=ary1[b];
  }
  cout<<max(ans1,ans2)<<endl;
}