#include<cstdio>
#define N 2000000000
int p,nr;
struct putere{int val,p;}v[60];
int citire()
{
	freopen("gfact.in","r",stdin);
	freopen("gfact.out","w",stdout);
	int n;
	scanf("%d%d",&n,&p);
	return n;
}
void desc(int n)
{
	for (int i=2; i<=n; ++i)
	{
		int putere=0;
		while (n%i==0)
		{
			n/=i;
			++putere;
		}
		v[++nr].val=i;
		v[nr].p=putere*p;
	}
	if (n!=1)
	{
		v[++nr].val=n;
		v[nr].p=p;
	}
	
}
bool zero(int x)
{
	for (int i=1; i<=nr; ++i)
	{
		int r=0;
		int cx=x;
		while (cx)
		{
			cx/=v[i].val;
			r+=cx;
		}
		if (r<v[i].p)
			return false;
			
	}
	return true;
}
int caut()
{
	int st=1,dr=N;
	while (st!=dr)
	{
		int m=(st+dr)>>1;
		if (!zero(m))
			st=m+1;
		else dr=m;
	}
	if (!zero(st)) return -1;
	return st;
}
int main()
{
	
	desc(citire());
	printf("%d",caut());
	return 0;
}