#!/usr/bin/python3


def gcd(a,b):
    if a < 0:
        a = -a
    if b < 0:
        b = -b

    while b != 0:
        a,b = b,a%b

    return a


def add(f1,f2):
    num = f1[0] * f2[1] + f1[1] * f2[0]
    den = f1[1] * f2[1]

    g = gcd(num,den)

    num = num // g
    den = den // g

    return [num,den]


def mul(f1,f2):
    num = f1[0] * f2[0]
    den = f1[1] * f2[1]

    g = gcd(num, den)

    num = num // g
    den = den // g

    return [num, den]


m,n,p = map(int,input().split(' '))

table = []

for i in range(n+1):
    table.append([])
    for j in range(p+1):
        table[i].append([0,1])

table[0][0] = [1,1]

for c in range(p):
    nBalls = m - c
    for r in range(n):
        nGood = 2 * (n - r)
        table[r+1][c+1] = add(table[r+1][c+1],mul(table[r][c], [nGood,nBalls]))
        table[r][c+1] = add(table[r][c+1],mul(table[r][c], [nBalls-nGood,nBalls]))

ans = mul(table[n-1][p-1],[2,(m - p + 1)])

#print(table)
#print(ans)
print(f'{ans[0]}/{ans[1]}')
#print(8.0/45)