//inlclude before define 
#define _USE_MATH_DEFINES

//include
#include<iostream>
#include<string>
#include<algorithm>
#include<vector>
#include<cmath>
#include<type_traits>
#include<numeric>
#include<deque>
#include<iomanip>
#include<set>
#include<unordered_set>
#include<tuple>
#include<map>
#include<memory>

using namespace std;

//typedef
typedef vector<int> VI;
typedef vector<string> VS;
typedef vector<char> VC;
typedef vector<double> VD;
typedef pair<int, int> P1;
typedef long long int ll;

//number
#define INF 1e9
#define NUM 1000000007

//itr
#define all(x) begin(x),end(x)

//repeat
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,a,b) for(int i=int(a);i<int(b);i++)
#define RREPS(i,x) for(int i=((int)(x));i>=0;i--)

//max,min
#define chmin(a,b) a=min((a),(b))
#define chmax(a,b) a=max((a),(b))

//function

/*ll gcd(ll a, ll b) {
	if (b == 0) return a;
	else return gcd(b, a%b);
}*/

/*ll lcm(ll a,ll b) {
	ll g = gcd(a, b);
	return a * (b / g);
}*/

/*int dig(int a) {
	int sum = 0;
	while (a) {
		sum += a % 10;
		a /= 10;
	}
	return sum;
}*/

//grid template
int x[] = { -1, 0, 1, 0 };
int y[] = { 0,-1,0,1 };
int xx[] = { -1,-1,1,1 };
int yy[] = { 1,-1,1,-1 };

int main() {
	string s;
	cin >> s;

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

	int cnt = 0;
	REP(i,1, s.size()) {
		if (s[i] == '3') {
			cnt++;
		} else {
			cout << -1 << endl;
			return 0;
		}
	}

	cout << cnt << endl;
}