#include <iostream>
#include <cmath>
using namespace std;
int GetLength(double x);
int main()
{
int n; cin>>n;
double y=1;
for(int x=2; x<=n; x++)
y=y*x;
cout<<GetLength(y)<<endl;
return 0;
}
int GetLength(double x)
{
int n=0;
while(x>=1) // !!!!
n++, x/=10;
return n;
}
int GetLength(int x)
{
int n; cin>>n;
double len=0;
for(int i=1; i<=n; i++)
len += log(i)/log(10);
cout << (int)len + 1;
return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
    int n;
    long long ans=1;
    double k=1; 
    cin>>n;
    while(n)
        if(k<10)
        {
            k*=n;
            n--;
        }
        else
        {
            ans++;
            k/=10;
        }
    cout<<ans;
    return 0;
}//时间复杂度 O(n) 

#include <iostream>
#include <cmath>
using namespace std;
int GetLength(double x);
int main()
{
int n; cin>>n;
double y=1;
for(int x=2; x<=n; x++)
y=y*x;
cout<<GetLength(y)<<endl;
return 0;
}
int GetLength(double x)
{
int n=0;
while(x>=1) // !!!!
n++, x/=10;
return n;
}
int GetLength(int x)
{
int n; cin>>n;
double len=0;
for(int i=1; i<=n; i++)
len += log(i)/log(10);
cout << (int)len + 1;
return 0;
}