import sys

input = sys.stdin.readline


def main():
    H, A, D = map(int, input().split())
    ans = H
    for i in range(0, (H+D-1)//D+1):
        n = max(0, H - i*D)
        j = (n+A-1)//A
        ans = min(ans, i*1.5+j)

    print(ans)


if __name__ == '__main__':
    main()