#include<algorithm>
#include<complex>
#include<ctype.h>
#include<iomanip>
#include<iostream>
#include<map>
#include<math.h>
#include<numeric>
#include<queue>
#include<set>
#include<stack>
#include<stdio.h>
#include<string>
#include<string>
#include<vector>

using namespace std;
typedef long long ll;

#define FOR(i,a,b) for(ll i=(a);i<(b);++i)
#define ALL(v) (v).begin(), (v).end()
#define p(s) cout<<(s)<<endl
#define p2(s, t) cout << (s) << " " << (t) << endl
#define br() p("")
#define pn(s) cout << (#s) << " " << (s) << endl
#define p_yes() p("YES")
#define p_no() p("NO")

template < typename T >
void vprint(T &V){
	for(auto v : V){
    	cout << v << " ";
	}
	cout << endl;
}

const ll mod = 1e9 + 7;
const ll inf = 1e18;

int main(){
    cin.tie(0);
    ios::sync_with_stdio(false);

    // input
    string s;
    cin >> s;

    if(s[0]!='1'){
        p(-1);
        return 0;
    }

    ll count = 0;
    ll L = s.size();
    FOR(i, 1, L){
        if(s[i]!='3'){
            p(-1);
            return 0;
        }
        else{
            count++;
        }
    }

    if(count==0){
        p(-1);
    }else{
        p(count);
    }

    return 0;
}