#include #include #include #include #include #include #include #include #include #include #include #include #include #include using namespace std; #define REP(i,a,n) for(int i=(a); i<(int)(n); i++) #define rep(i,n) REP(i,0,n) #define FOR(it,c) for(__typeof((c).begin()) it=(c).begin(); it!=(c).end(); ++it) #define ALLOF(c) (c).begin(), (c).end() typedef long long ll; double calc(int k){ return 3.0/2.0 * k; } int main(){ int H, A, D; cin >> H >> A >> D; double ret = 10e30; int x = 0; while(true){ int B = H-A*x; if(B<=0){ ret = min(ret, (double)x); break; } int k = B/D + ((B%D==0)?0:1); ret = min(ret, x + calc(k)); x++; } printf("%.6lf\n", ret); return 0; }