#include <iostream>
#include <vector>

void solve() {
    int h, a, d;
    std::cin >> h >> a >> d;

    std::vector<int> dp(h + 1, 0);
    for (int x = 1; x <= h; ++x) {
        dp[x] = std::min(dp[std::max(0, x - a)] + 2,
                         dp[std::max(0, x - d)] + 3);
    }

    int ans = dp[h];
    std::cout << ans / 2 << (ans % 2 == 0 ? "" : ".5") << "\n";
}

int main() {
    std::cin.tie(nullptr);
    std::ios::sync_with_stdio(false);

    solve();

    return 0;
}