# coding:utf-8
H, A, D = map(int,raw_input().split())

INF = 1e9+7
dp = [INF for _ in range(max(H,A,D)+1)]
for i in range(A+1): dp[i]=1.0
for i in range(A+1, D+1): dp[i]=1.5
for i in range(D+1, max(H,A,D)+1): dp[i]=min(dp[i-A]+1.0, dp[i-D]+1.5)

print dp[H]