#include <cstdio>
#include <map>
#include <queue>
using namespace std;

struct ITEM {
  int a, b, c;
  bool operator<(const ITEM &src) const {
    if (a != src.a) return a < src.a;
    if (b != src.b) return b < src.b;
    return c < src.c;
  }
};

struct NODE {
  ITEM water;
  int step;
};

int A, B, C, x;
queue<NODE> q;
map<ITEM, bool> vis;

int main() {
  freopen("pourwater.in", "r", stdin);
  freopen("pourwater.out", "w", stdout);
  scanf("%d %d %d %d", &A, &B, &C, &x);

  q.push({A, 0, 0, 0});

  while (!q.empty()) {
    NODE now = q.front();
    q.pop();

    if (now.water.a == x || now.water.b == x || now.water.c == x) {
      printf("%d\n", now.step);
      return 0;
    }

    if (vis[now.water]) continue;
    vis[now.water] = 1;

    int a = now.water.a, b = now.water.b, c = now.water.c;
    // printf("[%d %d %d %d]\n", a, b, c, now.step);

    // a -> b
    int pour = min(B - b, a);
    q.push({a - pour, b + pour, c, now.step + 1});

    // a -> c
    pour = min(C - c, a);
    q.push({a - pour, b, c + pour, now.step + 1});

    // b -> a
    pour = min(A - a, b);
    q.push({a + pour, b - pour, c, now.step + 1});

    // b -> c
    pour = min(C - c, b);
    q.push({a, b - pour, c + pour, now.step + 1});

    // c -> a
    pour = min(A - a, c);
    q.push({a + pour, b, c - pour, now.step + 1});

    // c -> b
    pour = min(B - b, c);
    q.push({a, b + pour, c - pour, now.step + 1});
  }

  printf("false\n");
  return 0;
}