#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 dfs(long long N,int cp = 0){
	if(N<0)N += 5;
	if(cp>=30)return -1;
	if(N==0)return 0;
	if(N%5==0){
		long long r = dfs(N/5,cp+1);
		if(r==-1)return r;
		return r*5;
	}
	if(N%5==1){
		long long ret = 1e18;
		;
		long long r = dfs(N/5,cp+1);
		if(r!=-1)ret = min(ret,r*5+1);
		r = dfs((N-16)/5,cp+1);
		if(r!=-1)ret = min(ret,r*5+4);
		if(ret==1e18)ret=  -1;
		return ret;
	}
	if(N%5==4){
		long long ret = 1e18;
		;
		long long r = dfs(N/5,cp+1);
		if(r!=-1)ret = min(ret,r*5+2);
		r = dfs((N-9)/5,cp+1);
		if(r!=-1)ret = min(ret,r*5+3);
		if(ret==1e18)ret=  -1;
		return ret;
	}
	return -1;
	
}
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;
		}
	}
	
	long long t = 1;
	rep(i,E)t *= 5;
	N %= t;
	if(N<0)N += t;
	long long ans = dfs(N);
	if(ans==-1)cout<<"NaN"<<endl;
	else {
		if(ans > (1LL<<29))ans -= t;
		cout<<ans<<endl;
	}
	//cout<<dfs(N)<<endl;
	
	return 0;
}