def read_data():
    age = int(input())
    p0, p1, p2 = map(int, input().split())
    return age, p0/100.0, p1/100.0, p2/100.0

def solve(age, p0, p1, p2, target=80):
    N = 16
    q0 = [0] * N
    q1 = [0, 1] + [0] * (N-2)
    q2 = [0] * (N-2) + [1, 0]
    q3 = [0, 0] + [1] * (N-4) + [0, 0]
    r0, r1, r2 = 1 - p0, 1 - p1, 1 - p2
    for y in range(target - age):
        qr0 = [q0i * r0 for q0i in q0]
        qr1 = [q1i * r1 for q1i in q1]
        qr2 = [q2i * r1 for q2i in q2]
        qr3 = [q3i * r2 for q3i in q3]
        nq0 = qr0[:]
        nq1 = [0] * N
        nq2 = [0] * N
        nq3 = qr3[:]
        for i in range(1, N-1):
            if q3[i-1] + q1[i-1]:
                s1 = (qr3[i-1] + qr1[i-1])/(q3[i-1] + q1[i-1])
            else:
                s1 = 0
            if q3[i+1] + q2[i+1]:
                s2 = (qr3[i+1] + qr2[i+1])/(q3[i+1] + q2[i+1])
            else:
                s2 = 0
            t2 = 1 - s2
            t1 = 1 - s1
            nq0[i] += qr1[i] * t2 + qr2[i] * t1 + qr3[i] * t2 * t1
            nq1[i] = (qr1[i] + qr3[i] * t1) * s2
            nq2[i] = (qr2[i] + qr3[i] * t2) * s1
            nq3[i] *= s1 * s2
        q0 = nq0
        q1 = nq1
        q2 = nq2
        q3 = nq3
    return 2 * (sum(q0) + sum(q1) + sum(q2) + sum(q3))
    
if __name__ == '__main__':
    age, p0, p1, p2 = read_data()
    print(solve(age, p0, p1, p2))