import sys
sys.setrecursionlimit(10 ** 6)
def II(): return int(sys.stdin.readline())
def LI(): return list(map(int, sys.stdin.readline().split()))
def LC(): return list(input())
def IC(): return [int(c) for c in input()]
def MI(): return map(int, sys.stdin.readline().split())
INF = float('inf')
def solve():
    H,R = map(float, sys.stdin.readline().split())
    import math
    S = -8.245 + 6.807 * H + 7.073 * (2*R * math.pi)
    print(S)
    return
solve()