H,A,D = map(int,input().split())

ans = 10 ** 10
i = 0
while True:
    tmp = i
    h = H - A * i
    if h <= 0:
        if tmp < ans:
            ans = tmp
        break
    q = (h + D - 1) // D
    tmp += q * 3 / 2
    if tmp < ans:
        ans = tmp
    i += 1
print(ans)