#include <iostream>
using namespace std;

int main(){
	int h, a, d;
	cin >> h >> a >> d;
	double dp[h + 1]{};
	for(int i = 1; i <= h; i++) dp[i] = min(dp[max(0, i - a)] + 1, dp[max(0, i - d)] + 1.5);
	cout << dp[h] << endl;
}