#include<iostream>
#include<string>
using namespace std;
int main()
{
    string n;
    cin>>n;
    for(int i=0;i<n.length();i++)
    if(n[i]==0||n[i]==0||n[i]==1||n[i]==2||n[i]==3||n[i]==4||n[i]==5||n[i]==6||n[i]==7||n[i]==8||n[i]==9||)
    {
        
    }
    else
    {
    cout<<"Invalid input";
    return 0;
    }
    cout<<n.length();
 
    
    return 0;
}