#include<bits/stdc++.h>

#define f first
#define s second
#define ll long long
#define pb push_back
#define sz(x) (int)(x).size()
#define all(x) x.begin(),x.end()

using namespace std;

int main(){
    ll y,l;
    scanf("%lld %lld",&y,&l);
    for(ll ans=l;ans<1000;ans++){
        vector<int> digs;
        ll tr=ans;
        while(tr){
            digs.pb(tr%10);
            tr/=10;
        }
        ll lb=11,rb=y;
        ll res=-1;
        while(lb<=rb){
            ll md=(lb+rb)/2;
            __int128 anss=0,tr=1;
            for(auto p:digs){
                if(tr>y){
                    anss=-1;
                    break;
                }
                anss+=tr*p;
                tr*=md;
            }
            if(anss>y){
                rb=md-1;
            }
            else{
                if(anss==y)res=md;
                lb=md+1;
            }
        }
        if(res!=-1){
            printf("%lld\n",res);
            return 0;
        }
    }
    for(int base=1e6;base>=10;base--){
        bool ok=1;
        __int128 ans=0,trs=1;
        ll tr=y;
        while(tr){
            ll dig=tr%base;
            tr/=base;
            if(dig>=10){
                ok=0;break;
            }
            ans+=dig*trs;
            trs*=10;
        }
        if(ok&&ans>=l){
            printf("%i\n",base);
            return 0;
        }
    }
}