#include<stdio.h>

long long i,j,n,k,a[30],nr,ok;

int main()
{
	freopen("light2.in","r",stdin);
	freopen("light2.out","w",stdout);
	
	scanf("%lld %lld",&n,&k);
	
	for(i=1;i<=k;i++)
		scanf("%lld",&a[i]);
	
	for(nr=0,i=1;i<=n;i++)
	{
		for(j=1,ok=-1;j<=k;j++)
			if(i%a[j]==0)
				ok*=-1;
		if(ok==1)
			nr++;
	}
	
	printf("%lld",nr);
	
	return 0;
}