#include<iostream>
#include <bits/stdc++.h>

#define ld long double
#define ll long long
#define rep(i, a, b) for(int i = a ; i < b ; i ++)
#define sz(v) (int)v.size()
#define all(v) begin(v), end(v)
#define IO ios_base::sync_with_stdio(0); cin.tie(0); cout.tie(0);
using namespace std;
const int N = 5e3 + 5;
const ll inf = 1e18;

ll solve(ll val, ll base) {
    ll ans = 0;
    vector<int> v;
    while (val) {
        if (val % base > 9) return 0;
        v.push_back(val % base);
        val /= base;
    }
    reverse(v.begin(), v.end());
    if (v.size() >= 19) return inf;
    for (auto i: v) {
        ans = ans * 10 + i;
    }
    return ans;
}

ll check(vector<int> &d, ll base) {
    ll sum = 0;
    ll p = 1;
    for (int i = 0; i < d.size(); i++) {
        // check if sum + p * d[i] > inf
        if ((sum + (ld) p * d[i]) > inf)return inf;
        sum += p * d[i];

        // check if p * base > inf
        if (i + 1 < d.size()) {
            if (base > inf / p) return inf;
            p *= base;
        }
    }
    return sum;
}

void doWork() {
    ll y, l;
    cin >> y >> l;
    ll ans = 0;
    for (ll i = l; i <= 999; i++) {
        vector<int> temp;
        int x = i;
        while (x) {
            temp.push_back(x % 10);
            x /= 10;
        }
        ll low = 2, high = 1e18;
        while (low < high) {
            ll mid = low + high + 1 >> 1;
            if (check(temp, mid) > y) high = mid - 1;
            else low = mid;
        }
        if (check(temp, low) == y) ans = max(ans, low);
    }

    for (ll i = 1e6; i > ans; i--) {
        if (solve(y, i) >= l) {
            ans = i;
            break;
        }
    }
    cout << ans;
}

int main() {
    IO
    int t = 1;
//    cin >> t;
    for (int i = 1; i <= t; i++) {
        //  cout << "Case #" << i << ": ";
        doWork();
    }
}