#include <iostream>
#include <string>
#include <cctype>
using namespace std;
int main(){
    string s;
    cin>>s;
    int start==0;
    if(s[0]=='-'||s[0]=='+'){
        if(s.length()==1){
            cout<<"Invalid input";
        }
        start=1;
    }
    for(int i=start; i<s.lenghr();i++){
        if(!isdigit(s[i])){
            cout<<"Invalid input";
        }
    }
    cout<<(s.lenght()-start);
}