n, m ,p, q = [int(_) for _ in input().split()]

l = []
for i in range(p, p+q):
    l.append(i)

ans = []
for i in range(1, 13):
    if i in l:
        ans.append([i, m*2])
    else:
        ans.append([i, m])

x = n
for i in range(100000):
    for j in ans:
        x -= j[1]
        if x <= 0:
            print(i*12+j[0])
            break
    if x <= 0:
        break