#include<iostream>
using namespace std;
int main()
{
    int a,c;
    cin>>a;
    if(a={0,1,2,3,4,5,6,7,8,9})
    //if(a={0,1,2,3,4,5,6,7,8,9}||a={'a','b','c','d','e','f','g','h','i','j','k','l','m','n','o','p','q','r','s','t','u','v','w','x','y','z'}||a={'A','B','C','D','E','F','G','H','I','J','K','L','M','N','O','P','Q','R','S','T','U','V','W','X','Y','Z'})
    {
        c=a.length();
        cout<<c;
    }
    else
    {
        cout<<"Invalid input";
    }
}