note.py

# coding: utf-8

def func(n, m, N):
    def state(cnt, acc):
        if N == cnt:
            return acc
        else:
            return state(cnt + 1, (1 - 1/n - 1/m) * acc + 1/m)
    return state(0, 1)

def generalize(n, m, N):
    alph = (n / (n + m))
    if N == 0:
        return 1.0
    else:
        return alph + (1 - alph) * pow(1 - 1/n - 1/m, N)

if __name__ == '__main__':
    n, m, N = [float(num) for num in raw_input().split(' ')]
    print generalize(n, m, N)