#include "bits/stdc++.h"
#pragma GCC optimize ("O3")
#pragma GCC target ("sse4")
 
using namespace std;
 
typedef long long ll;
typedef long double ld;
typedef complex<ld> cd;
 
typedef pair<int, int> pi;
typedef pair<ll,ll> pl;
typedef pair<ld,ld> pd;
 
typedef vector<int> vi;
typedef vector<ld> vd;
typedef vector<ll> vl;
typedef vector<pi> vpi;
typedef vector<pl> vpl;
typedef vector<cd> vcd;

template<class T> using pq = priority_queue<T>;
template<class T> using pqg = priority_queue<T, vector<T>, greater<T>>;
 
#define FOR(i, a, b) for (int i=a; i<(b); i++)
#define F0R(i, a) for (int i=0; i<(a); i++)
#define FORd(i,a,b) for (int i = (b)-1; i >= a; i--)
#define F0Rd(i,a) for (int i = (a)-1; i >= 0; i--)
#define trav(a,x) for (auto& a : x)
#define uid(a, b) uniform_int_distribution<int>(a, b)(rng)
 
#define sz(x) (int)(x).size()
#define mp make_pair
#define pb push_back
#define f first
#define s second
#define lb lower_bound
#define ub upper_bound
#define all(x) x.begin(), x.end()
#define ins insert

template<class T> bool ckmin(T& a, const T& b) { return b < a ? a = b, 1 : 0; }
template<class T> bool ckmax(T& a, const T& b) { return a < b ? a = b, 1 : 0; }
 
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());

void __print(int x) {cerr << x;}
void __print(long x) {cerr << x;}
void __print(long long x) {cerr << x;}
void __print(unsigned x) {cerr << x;}
void __print(unsigned long x) {cerr << x;}
void __print(unsigned long long x) {cerr << x;}
void __print(float x) {cerr << x;}
void __print(double x) {cerr << x;}
void __print(long double x) {cerr << x;}
void __print(char x) {cerr << '\'' << x << '\'';}
void __print(const char *x) {cerr << '\"' << x << '\"';}
void __print(const string &x) {cerr << '\"' << x << '\"';}
void __print(bool x) {cerr << (x ? "true" : "false");}

template<typename T, typename V>
void __print(const pair<T, V> &x) {cerr << '{'; __print(x.first); cerr << ", "; __print(x.second); cerr << '}';}
template<typename T>
void __print(const T &x) {int f = 0; cerr << '{'; for (auto &i: x) cerr << (f++ ? ", " : ""), __print(i); cerr << "}";}
void _print() {cerr << "]\n";}
template <typename T, typename... V>
void _print(T t, V... v) {__print(t); if (sizeof...(v)) cerr << ", "; _print(v...);}
#ifdef DEBUG
#define dbg(x...) cerr << "\e[91m"<<__func__<<":"<<__LINE__<<" [" << #x << "] = ["; _print(x); cerr << "\e[39m" << endl;
#else
#define dbg(x...)
#endif


const int MOD = 1000000007;
const char nl = '\n';
const int MX = 100001; 

ll mul(ll A, ll B) {
    if (A == 0 || B == 0) return 0;
    if (log10(A) + log10(B) > 18.3) return 2e18;
    return A*B;
}
ll add(ll A, ll B) {
    return min(A+B, (ll) 2e18);
}

void solve() {
    ll Y, L; cin >> Y >> L;
    ll ans = 10;
    FOR(i, 10, 1000110) {
        vl digs;
        ll cur = Y;
        ll res = 0;
        while (cur) {
            if (cur%i >= 10) goto done;
            digs.pb(cur%i);
            cur /= i;
        }
        reverse(all(digs));
        res = 0; trav(a, digs) {
            res *= 10; res += a;
        }
        if (res >= L) {
            ans = i;
        }
        done:;
    }

    F0R(a, 10) {
        F0R(b, 10) {
            F0R(c, 10) {
                if (100*a+10*b+c < L) continue;
                ll lo = 2, hi = 2e18;
                while (lo < hi) {
                    ll mid = (lo+hi+1)/2;
                    if (add(c, add(mul(b, mid), mul(mul(mid, mid), a))) <= Y) {
                        lo = mid;
                    } else hi = mid-1;
                }
                if (add(c, add(mul(b, lo), mul(mul(lo, lo), a))) == Y) {
                    ckmax(ans, lo);
                }
            }
        }
    }
    cout << ans << nl;

}
 
int main() {
    ios_base::sync_with_stdio(0); cin.tie(0);

    int T = 1;
//    cin >> T;
    while(T--) {
        solve();
    }

	return 0;
}