#include<bits/stdc++.h>
using namespace std;

int main(){
    int c;
    c = getchar();
    if(c != '1')return 0 & puts("-1");
    long i = 1;
    c = getchar();
    while(c == '3'){
        ++i;
        c = getchar();
        if('0' <= c && c <= '9' && c != '3')return 0 & puts("-1");
    }
    cout << i << endl;
    return 0;
}