#!/usr/bin/env python3
# %%
import sys
read = sys.stdin.buffer.read
readline = sys.stdin.buffer.readline
readlines = sys.stdin.buffer.readlines


# %%
H, A, D = map(int, read().split())

# %%
dp = [0] * (H + 1100)
for n in range(1, H + 1):
    x = 1.5 + dp[n - D]
    y = 1.0 + dp[n - A]
    dp[n] = min(x, y)

# %%
print(dp[H])