#include "bits/stdc++.h"
using namespace std;

typedef long long Int;
#define REP(i,n) for(int (i)=0;(i)<(int)(n);++(i))


int H, A, D;
double dp[10001];
bool mark[10001];

double f(int h) {
	if (h <= 0) return 0;
	if (mark[h]) return dp[h];
	double res = min(
		1 + f(h-A),
		1.5 + f(h - D)
	);
	mark[h] = true;
	return dp[h] = res;
}

int main() {
	cin >> H >> A >> D;
	printf("%f\n", f(H));
}