#include <stdio.h>
#define MAX (long long int)1e16

int main()
{
	long long int a,b,c,d,e,f;
	scanf("%lld%lld%lld%lld%lld%lld",&a,&b,&c,&d,&e,&f);
	
	long long int ans = MAX;
	for(long long int i=0;i<=a;i++)
	{
		long long int min = 0, max = b;
		while(min<=max)
		{
			long long int h = (min+max)/2;
			long long int C1 = h/d, C2 = i/c;
			if(h%d!=0) C1++;
			if(i%c!=0) C2++;
			long long int S = i*C1 + h*C2;
			if(a*b - i*h <= C1 * f + C2 * e)
			{
				ans = ans<C1+C2?ans:C1+C2;
				max = h-1;
			}
			else min = h+1;
		}
	}
	printf("%lld",ans);
}