// editor5
#include <iostream>
#include <string>
#include <cctype>
using namespace std;
int main() 
{
    string input;
    cin >> input;
    
    bool valid = true;
    int start = 0;
    
    if (input[0] == '-')
    {
        start = 1;
    }
    for (int i = start; i<input.size(); ++1)
    {
        if(!isdigit(input[i]))
        {
            valid = false;
            break;
        }
        
    }
    if (!valid || input == "-" || input.size() == 0)
    {
        cout << "Invalid input";
        return 0;
    }
    int num = stoi(input);
    if (num < -10000 || num >10000) {
        cout << "Invalid input";
        return 0;
    }
    int digits = (num == 0) ? 1 : to_string(abs(num)).size();
    
    cout << digits;
    return 0;
}