#include <stdio.h>
#include <atcoder/all>
#include <bits/stdc++.h>
using namespace std;
using namespace atcoder;
using mint = modint;
#define rep(i,n) for (int i = 0; i < (n); ++i)
#define Inf32 1000000001
#define Inf64 4000000000000000001
long long t = 1;
set<long long> S;
void dfs(long long N,long long cv = 0,long long c5 = 1,long long c2 = t){
	N %= c2;
	while(N<0)N += c2;
	if(c2==0)return;
	if(N%c2==0){
		S.insert(cv);
		return;
	}
	
	if(N%5==0){
		dfs(N/5,cv,c5*5,c2/5);
	}
	else if(N%5==1){
		dfs((N-1)/5,cv+c5,c5*5,c2/5);
		dfs((N-16)/5,cv+c5*4,c5*5,c2/5);
	}
	else if(N%5==4){
		dfs((N-4)/5,cv+c5*2,c5*5,c2/5);
		dfs((N-9)/5,cv+c5*3,c5*5,c2/5);
	}
	
}
int main(){
	
	long long N,E;
	cin>>N>>E;
	
	if(N>=0){
		long long sq = sqrtl(N);
		if(sq*sq==N){
			cout<<sq<<endl;
			return 0;
		}
	}
	
	
	rep(i,E)t *= 5;
	N %= t;
	if(N<0)N += t;
	dfs(N);
	//cout<<S.size()<<endl;
	for(auto a:S){
		long long tt = a;
		tt %= t;
		while(tt>(1LL<<29))tt -= t;
		while(tt<-(1LL<<29))tt += t;
		if((-(1LL<<29)<=tt && tt<=(1LL<<29))){
			cout<<tt<<endl;
			return 0;
		}
	}
	
	cout<<"NaN"<<endl;
	
	return 0;
}