nodes = [(i, (i + 1) % 100, (i + 2) % 100) for i in range(100)]
c = 0
t = 0
for i in range(0, 100):
    for j in range(i + 1, 100):
        for n in nodes:
            if i in n and j in n:
                c = c + 1
            t = t + 1
print(c/float(t))