#include <bits/stdc++.h>
using namespace std;

template<typename T, typename U>
using pv=vector<pair<T,U>>;
template<typename T>
using matrix=vector<vector<T>>;
template<typename T>
using pque=priority_queue<T>;
template<typename T>
using lpque=priority_queue<T,vector<T>,greater<T>>;

using ll=long long;
using intpair=pair<int,int>;
using llpair=pair<ll,ll>;
using ilpair=pair<int,ll>;
using lipair=pair<ll,int>;
using intvec=vector<int>;
using llvec=vector<ll>;
using intq=queue<int>;
using llq=queue<ll>;
using intmat=vector<intvec>;
using llmat=vector<llvec>;

#define PI 3.141592653589793
#define INTINF ((1<<30)-1)
#define LLINF ((1LL<<62)-1)
#define MPRIME 1000000007
#define MPRIME9 998244353
#define MMPRIME ((1ll<<61)-1)

#define len length()
#define pushb push_back
#define fi first
#define se second

#define all(name) name.begin(),name.end()
#define rall(name) name.rbegin(),name.rend()
#define gsort(vbeg,vend) sort(vbeg,vend,greater<>())

template<class T>
inline bool chmin(T& a, T b) {
	if (a > b) {
		a = b;
		return true;
	}
	return false;
}

template<class T>
inline bool chmax(T& a, T b) {
	if (a < b) {
		a = b;
		return true;
	}
	return false;
}

template<class T>
inline void init(T& v) {
	for(auto &a: v) cin>>a;
}
template<class T, class U>
inline void init(vector<pair<T,U>>& v) {
	for(auto &a: v) cin>>a.first>>a.second;
}
template<class T, class N>
inline void init(T& v, N n) {
	v.resize(n);
	for(auto &a: v) cin>>a;
}
template<class T, class U, class N>
inline void init(vector<pair<T,U>>& v, N n) {
	v.resize(n);
	for(auto &a: v) cin>>a.first>>a.second;
}

template<class T>
inline void out(T a) {
	cout<<a<<endl;
}
template<class T, class... U>
inline void out(T a, U... alist) {
	cout<<a<<" ";
	out(forward<U>(alist)...);
}

template<class N>
void resiz(N n) {
	//empty
}
template<class N, class T, class... U>
void resiz(N n, T&& hd, U&&... tl) {
	hd.resize(n);
	resiz(n,forward<U>(tl)...);
}

ll binpow(ll a, ll ex, ll p) {
	ll result=1;
	while(ex>0) {
		if(ex&1) result=result*a%p;
		ex>>=1;
		a=a*a%p;
	}
	return result;
}


ll A;
ll ans=LLINF;

void input() {
	cin>>A;
}

void solve() {
	for(ll N=2; ; N++) {
		ll mul=1, M=1;
		while((A-1)/mul >= N) { mul*=N; M++; }
		chmin(ans,N*M);
		if(N>M) break;
	}
	cout<<ans<<endl;
}

int main() {
	cin.tie(nullptr);
	ios_base::sync_with_stdio(false);
	cout<<fixed<<setprecision(15);
	int t=1;
	while(t) {
		input();
		solve();
		t--;
	}
}