#include <bits/stdc++.h>
#define all(vec) vec.begin(),vec.end()
#define mp make_pair
using namespace std;
using ll=long long;
using P=pair<ll,ll>;
const ll INF=1LL<<30;
const ll LINF=1LL<<62;
const double eps=1e-9;
const ll MOD=1000000007LL;
template<typename T>void chmin(T &a,T b){a=min(a,b);};
template<typename T>void chmax(T &a,T b){a=max(a,b);};
int dx[4]={0,1,0,-1};
int dy[4]={1,0,-1,0};
int main(){
	string s;cin>>s;
	bool f=false;
	for(int i=1;i<s.length();i++){
		if(s[i]!='3')f=true;
	}
	if(s[0]!='1')f=true;
	if(s.length()==1)f=true;
	if(f){
		cout<<-1<<endl;
		return 0;
	}
	cout<<s.length()-1<<endl;
}