#include <algorithm>
#include <cassert>
#include <cctype>
#include <chrono>
#define _USE_MATH_DEFINES
#include <cmath>
#include <cstdio>
#include <cstring>
#include <ctime>
#include <deque>
#include <functional>
#include <iostream>
#include <map>
#include <queue>
#include <random>
#include <set>
#include <sstream>
#include <string>
#include <tuple>
#include <vector>
using namespace std;

#define FOR(i,m,n) for(int i=(m);i<(n);++i)
#define REP(i,n) FOR(i,0,n)
#define ALL(v) (v).begin(),(v).end()

const int INF = 0x3f3f3f3f, MOD = 1000000007;
const long long LINF = 0x3f3f3f3f3f3f3f3fLL;
/*-----------------------------------------*/
int main() {
  cin.tie(0); ios::sync_with_stdio(false);
  // freopen("input.txt", "r", stdin);

  string n; cin >> n;
  if (n.front() != '1' || n == "1") {
    cout << -1 << '\n';
    return 0;
  }
  int ans = 0, sz = n.length();
  FOR(i, 1, sz) {
    if (n[i] == '3') ++ans;
    else {
      cout << -1 << '\n';
      return 0;
    }
  }
  cout << ans << '\n';
  return 0;
}