h, a, d = map(int, input().split())

dp = [1.0e15 for _ in range(h + 1)]
dp[h] = 0.0
for cur in range(h, 0, -1):
  nxt = max(0, cur - a)
  dp[nxt] = min(dp[nxt], dp[cur] + 1.0)
  nxt = max(0, cur - d)
  dp[nxt] = min(dp[nxt], dp[cur] + 1.5)

print(dp[0])