#include<iostream>
#include<string>
using namespace std;
int main()
{
    string input;
    cin>>input;
    int count=0;
    for (int i=0;i<input.length();i++)
    {
        if(i==0 && input[i]=='-')
    {
        continue;
    }
    if (!isdigit(input[i]))
    {
        cout<<"Invalid input";
        return 0;
    }
    cout++;
}
if (input=="-")
{
    cout<<<"Invalid input";
    return 0;
}
cout<<count;
return 0;
}