#include <bits/stdc++.h>
using namespace std;

#define SZ(a) (int)a.size()
#define ALL(a) a.begin(), a.end()
#define FOR(i, a, b) for (LL i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (LL i = (b)-1; i>=(a); --i)
#define MP make_pair
#define PB push_back
#define F first
#define S second
#define FILL(a, b) memset(a, b, sizeof(a))

typedef long long LL;
typedef pair<int, int> PII;
typedef vector<int> VI;


const LL LINF = 1.1e18;
LL y, l;

__int128 f(int x, LL b)
{
	__int128 res = 0;
	__int128 o = 1;
	while (x)
	{
		int k = x % 10;
		res += k * o;
		x /= 10;
		if(x)
			o *= b;
	}
	return res;
}

void check(LL x)
{
	LL L = 2, R = LINF;
	while (L + 1 < R)
	{
		LL m = (L + R) / 2;
		if (y < f(x, m))
			R = m;
		else
			L = m;
	}
	if (f(x, L) == y)
	{
		cout << L << '\n';
		exit(0);
	}
}

bool ok(int b, LL x)
{
	__int128 B = 1;
	LL ans = 0;
	while (B * b <= x) B *= b;
	while (B)
	{
		LL k = x / B;
		if (k > 9) return false;
		ans *= 10;
		ans += k;
		x -= B * k;
		B /= b;
	}
	return ans >= l;
}

int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	
	cin >> y >> l;
	FOR (i, l, 1000)
	{
		check(i);
	}
	RFOR (b, 1e6 + 1, 2)
	{
		if (ok(b, y))
		{
			cout << b << '\n';
			break;
		}
	}
	
	return 0;
}