宝箱

// by BNU_LZM
#include<cstdio>
#include<algorithm>
using namespace std;

int main()
{
	int n, s1, s2, v1, v2;
	scanf("%d%d%d%d%d", &n, &s1, &v1, &s2, &v2);
	long long ans = 0;
	if(s1 > s2) { swap(s1, s2); swap(v1, v2); }
	if(n/s2 > 65536)
	{
		for(long long i = 0; i <= s1; i++) ans = max(ans, v2*i+(n-i*s2)/s1*v1);
		for(long long i = 0; i <= s2; i++) ans = max(ans, v1*i+(n-i*s1)/s2*v2);
	}
	else
	{
		for(long long i = 0; i*s2 <= n; i++) ans = max(ans, v2*i+(n-s2*i)/s1*v1);
	}
	printf("%lld\n", ans);
	return 0;
}