#include <bits/stdc++.h>
using namespace std;
const int N=1919810;
typedef long long ll;
typedef pair<ll,ll> PII;
ll n,y,b,d;
ll ans;

bool cal(vector<ll> &a,double jz){
    double sum=0,item=1;
    for(int i=0;i<a.size();i++){
        sum+=a[i]*item;
        if(sum>n) return true;
        item*=jz;
    }
    return sum>n;
}

double gao1(){
    vector<ll> v;
    ll yy=y;
    while(yy){
        v.push_back(yy%10);
        yy/=10;
    }
    double l=0,r=1e18;
    for(int i=0;i<200;i++){
        double mid=(l+r)/2;
        if(cal(v,mid)) r=mid;
        else l=mid;
        
    }
    return l;
}


bool gao2(ll x){
    vector<ll> v;
    ll xx=x;
    while(xx){
        v.push_back(xx%10);
        xx/=10;
    }
    ll l=0,r=1e18;
    while(l<r){
        ll mid=(l+r)/2;
        if(cal(v,mid)) r=mid;
        else l=mid+1;
    }
    
    ll sum=0,item=1;
    for(int i=0;i<v.size();i++){
        sum+=v[i]*item;
        item*=l;
    }
    if(n==sum){
        ans=l;
        return true;
    }
    l++;
    sum=0,item=1;
    for(int i=0;i<v.size();i++){
        sum+=v[i]*item;
        item*=l;
    }
    if(n==sum){
        ans=l;
        return true;
    }
    l-=2;
    sum=0,item=1;
    for(int i=0;i<v.size();i++){
        sum+=v[i]*item;
        item*=l;
    }
    if(n==sum){
        ans=l;
        return true;
    }
    return false;
}


bool gao3(ll x){
    ll nn=n;
    while(nn){
        if(nn%x>=10) return false;
        nn/=x;
    }
    return true;
}

int main() {
	cin>>n>>y;
	b=ceil(gao1());//jz
	
	    for(int i=y;i<=1000&&i<=n;i++){//ans
	        if(gao2(i)){
	            cout<<ans<<endl;
	            return 0;
	        }
	    }
	if(b>=1e5) b=1e5;    
	
	while(b>10){
	    if(gao3(b)){
	        cout<<b<<endl;
	        return 0;
	    }
	    b--;
	}
}