#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 (int i = (a); i<(b); ++i)
#define RFOR(i, b, a) for (int 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;


int main()
{
	ios::sync_with_stdio(false);
	cin.tie(0);
	LL y, lower, b = 10;
	cin >> y >> lower;
	FOR(d0, 0, 10) {
		FOR(d1, 0, 10) {
			FOR(d2, 0, 10) {
				if (d0 + 10 * d1 + 100 * d2 < lower) {
					continue;
				}
				LL l = 2, r = LINF;
				while (r - l > 1) {
					LL m = (l + r) / 2;
					bool tooBig = false;
					if (d1 != 0 && (double)d1 * m > LINF) {
						tooBig = true;
					}
					if (d2 != 0 && (double)d2 * m * m > LINF) {
						tooBig = true;
					}
					if (tooBig || d0 + d1 * m + d2 * m * m > y) {
						r = m;
					}
					else {
						l = m;
					}
				}
				if (d0 + d1 * l + d2 * l * l == y && d0 < l && d1 < l && d2 < l) {
					b = max(b, l);
				}
			}
		}
	}
	RFOR(c, 1'000'047, 10) {
		vector<int> digits;
		LL cur = y;
		bool ok = true;
		while (cur) {
			digits.push_back(cur % c);
			ok &= (cur % c) < 10;
			cur /= c;
		}
		if (!ok) {
			continue;
		}
		LL ans = 0;
		double dbAns = 0;
		reverse(ALL(digits));
		for (int d : digits) {
			ans = 10 * ans + d;
			dbAns = 10 * dbAns + d;
		}
		if (dbAns < LINF && ans >= lower) {
			b = max(b, (LL)c);
		}
	}
	cout << b << "\n";
	return 0;
}