#include <iostream>
using namespace std;
int main()
{
    char n[102] = {0};
    cin >> n;
    if(n[0] != '1'){
        cout << -1 << endl;
        return 0;
    }
    int ans = 0, i = 1;
    while(n[i] != 0){
        if(n[i] == '3') ++ans;
        else{
            cout << -1 << endl;
            return 0;
        }
        ++i;
    }
    cout << ans << endl;
    return 0;
}