#define _USE_MATH_DEFINES
 
#include <iostream>
#include <iomanip>
#include <sstream>
 
#include <algorithm>
#include <cmath>
 
#include <string>
//#include <array>
#include <list>
#include <queue>
#include <vector>
#include <complex>
#include <set>
#include <map>
 
/////////
#define REP(i, x, n) for(int i = x; i < n; i++)
#define rep(i,n) REP(i,0,n)
#define P(p) cout<<(p)<<endl;
 
#define PII pair<int,int>
/////////
typedef long long LL;
typedef long double LD;
/////////
using namespace::std;
/////////
const int dpmax = 15000;
int dp[dpmax+1];

int main(void){
    std::cin.tie(0); 
    std::ios::sync_with_stdio(false);
    std::cout << std::fixed;//
    cout << setprecision(16);//
	
	int T,N;
	cin>>T>>N;
	int c[15],v[15];
	vector<PII> vec;
	vec.reserve(15);
	rep(i,N){cin>>c[i];}
	rep(i,N){cin>>v[i];}
	rep(i,N){
		vec.push_back(PII(c[i],v[i]));
	}
	
	vector<PII>::iterator itr = vec.begin();
	int vv = itr->second;
	int vsum = 0;
	int tsum = 0;

	for(;itr != vec.end();++itr ){
		for(int i=dpmax;i>=0;--i){
			if( i==0 || dp[i] ){
				vv   = itr->second;
				vsum = 0;
				tsum = 0;
				while( vv ){
					tsum += itr->first;
					vsum += vv;
					if( dp[i] + tsum > T){
						break;
					}
					if( dp[i+vsum] == 0){
						dp[i+vsum] = dp[i] + tsum;
					}else{
						dp[i+vsum] = min( dp[i+vsum],dp[i] + tsum);
					}
					vv /= 2;
				}
			}
		}
	}

	int i = dpmax;
	for(;i>=0;--i){
		if( dp[i] ){
			break;
		}
	}
	P(i);
	return 0;
}