l1 = int(input())
r1 = int(input())
l2 = int(input())
r2 = int(input())
l3 = int(input())
r3 = int(input())
a1 = 1
a2 = 2
a3 = 3
ans = 100
if l2 <= l1 and l2 <= l3:
    lx = l2
    rx = r2
    l2 = l1
    r2 = r1
    l1 = lx
    r1 = rx
    a1 = 2
    a2 = 1
elif l3 <= l1 and l3 <= l2:
    lx = l3
    rx = r3
    l3 = l1
    r3 = r1
    l1 = lx
    r1 = rx
    a1 = 3
    a3 = 1
if l3 <= l2:
    lx = l2
    rx = r2
    l2 = l3
    r2 = r3
    l3 = lx
    r3 = rx
    x = a3
    a3 = a2
    a2 = x
if l3 <= r1 or l2 <= r1 and l3 <= r2:
    print(0)
else:
    if l2 <= r1:
        if r1 - l1 >= l3 - r2:
            ans = min(a1, ans)
        if r2 - l2 >= l3 - r1:
            ans = min(a2, ans)
        ans = min(a3, ans)
    elif l3 <= r2:
        if r3 - l3 >= l2 - r1:
            ans = min(a3, ans)
        if r2 - l2 >= l3 - r1:
            ans = min(a2, ans)
        ans = min(a1, ans)
    else:
        if l2 - r1 <= r3 - l3:
            ans = min(a3, ans)
        if l3 - r2 <= r1 - l1:
            ans = min(a1, ans)
    if ans == 100:
        print(-1)
    else:
        print(ans)