#include <bits/stdc++.h>

using namespace std;
int m1, m2, m3, l;
set<pair<int, int> > volt;
queue<pair<pair<int, int>, int> > q;
void pb(int a, int b, int db) {
    if (volt.find({a, b})==volt.end()) {
        volt.insert({a, b});
        q.push({{a, b}, db});
    }
}
int main()
{
    cin >> m1 >> m2 >> m3 >> l;
    pb(m1, 0, 0);
    while (q.size()>0) {
        int a=q.front().first.first, b=q.front().first.second, c=m1-a-b, db=q.front().second;
        q.pop();
        if (a==l || b==l || c==l) {
            cout << db << "\n";
            return 0;
        }
        db++;

        int kul=min(a, m2-b);
        pb(a-kul, b+kul, db);

        kul=min(m1-a, b);
        pb(a+kul, b-kul, db);

        kul=min(a, m3-c);
        pb(a-kul, b, db);

        kul=min(m1-a, c);
        pb(a+kul, b, db);

        kul=min(b, m3-c);
        pb(a, b-kul, db);

        kul=min(m2-b, c);
        pb(a, b+kul, db);

    }
    cout << -1 << "\n";
    return 0;
}