// editor5
#include<iostream>
#include<cmath>
using namespace std;
int main()
{
    string s;
    cin>>s;
    bool vaild =true;
    int i=(s[0]=='-')?1:0;
    for(;i<s.size();i++)
    if(!isdigit(s[i])) valid=false;
    if(!valid)cout<<"Invalid input";
    else
    {
        int n=stoi(s);
        if(n<-10000||n>10000) cout<<
        "Invalid input";
        else cout<<((n==0)? 1 :(int)log10(abs(n))+1);
        
    }
    return 0;
}