#include <bits/stdc++.h>
#define FOR(i,a,b) for (int i=(a);i<(b);i++)
#define FORR(i,a,b) for (int i=(a);i>=(b);i--)
#define pb push_back
#define pcnt __builtin_popcount
#define show(x) cout<<#x<<" = "<<x<<endl;
#define maxs(x,y) x = max(x,y)
#define mins(x,y) x = min(x,y)
#define fi first
#define se second
#define rng(a) (a.begin()),(a.end())
#define each(it,c) for(__typeof((c).begin()) it=(c).begin();it!=(c).end();it++)
#define sz(x) (int)(x).size()
#define mp make_pair

using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<vi> vvi;
typedef vector<pii> vpii;
typedef set<int> si;
typedef pair<ll,ll> pll;
typedef vector<ll> vl;
typedef vector<vl> vvl;
typedef vector<pll> vpll;
typedef set<ll> sl;
typedef __int128_t lll;
typedef pair<lll,lll> plll;
typedef vector<lll> vlll;
template<typename T>string join(vector<T>&v)
{stringstream s;FOR(i,0,sz(v))s<<' '<<v[i];return s.str().substr(1);}
ll gcd(ll a,ll b){if(a>b)swap(a,b);for(;a>0;b%=a,swap(a,b));return b;}
int modpow(ll a,ll n,int m){if(a==0)return a;ll p=1;for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;return(int)p;}
void dout(double d){printf("%.12f\n",d);}

const int iinf = 1e9;
const ll linf = 1e18;
const int mod = 1e9+7;
const double pi = acos(-1);
const double eps = 1e-10;

struct Prime{
  vl pl;
  random_device rnd;
  mt19937_64 mt;
  Prime(){
    mt = mt19937_64(rnd());
  }
  __int128_t mp(ll _a,ll n,ll m){
    if(_a==0)return 0;
    __int128_t a=_a, p=1;
    for(;n>0;n/=2,a=a*a%m)if(n&1)p=p*a%m;
    return p;
  }
  bool miller_rabin(ll _n){
    __int128_t n, t, y;
    ll a, d;
    _n = abs(_n);
    if(_n==2) return true;
    if(_n==1||(_n&1)==0) return false;
//    cout << "miller::" << _n << endl;
    uniform_int_distribution<ll> dist(1, _n-1);
    n = __int128_t(_n);
    d = _n-1;
    while((d&1)==0) d>>=1;
//    cout << "d::" << d << endl;
    FOR(i, 0, 100){
      a = dist(mt);
      t = d;
      y = mp(a,t,_n);
      while(t != _n-1 && y != 1 &&y != n-1){
        y = (y*y)%_n;
        t <<= 1;
      }
      if(y != _n-1 && (t&1) == 0) return false;
    }
    return true;
  }
  bool is_prime(ll a){
    if(a < 2)return false;
    each(itr, pl){
      if(*itr * *itr > a)return true;
      if(a%*itr == 0)return false;
    }
    return true;
  }
  void init(int a){
    pl.resize(0);
    pl.pb(2);
    pl.pb(3);
    int i = 5;
    while(i <= a){
      if(is_prime(i)) pl.pb(i);
      i += 2;
      if(is_prime(i)) pl.pb(i);
      i += 4;
    }
  }
  void prime_division(ll a, vpii&v){ // vに素因数分解の結果が入る
    v.resize(0);
    for(vl::iterator itr = pl.begin(); *itr * *itr <= a; itr++){
      if(a%*itr == 0){
        ll c = 0;
        while((a%*itr) == 0){
          a /= *itr;
          c++;
        }
        v.pb(pii(*itr, c));
      }
    }
    if(a > 1)v.pb(pii(a, 1));
  }
  void divisor(ll a, vl&v){ // v に約数が入る
    v.pb(1);
    for(vl::iterator itr = pl.begin(); *itr * *itr <= a; itr++){
      if(a%*itr == 0){
        ll b = 1, vs = sz(v);
        while((a%*itr) == 0){
          a /= *itr;
          b *= *itr;
          FOR(j, 0, vs)v.pb(v[j] * b);
        }
      }
    }
    if(a>1){
      int vs = sz(v);
      FOR(j, 0, vs)v.pb(v[j] * a);
    }
  }
};
ll n;
vl v;
Prime prime;
main(){
  cin.tie(0);
  ios::sync_with_stdio(false);
  prime.init(100100);
  cin >> n;
  prime.divisor(n, v);
  ll minv = linf;
  each(itr, v) mins(minv, max(*itr, n / *itr));
  int ans = 0;
  while(minv > 0)ans++, minv /= 10;
  cout << ans << endl;
  return 0;
}

Measured memory_bytes: 636