There are n boys and m girls attending a theatre club. To set a play "The Big Bang Theory", they need to choose a group containing exactly t actors containing no less than 4 boys and no less than one girl. How many ways are there to choose a group? Of course, the variants that only differ in the composition of the troupe are considered different.

Perform all calculations in the 64-bit type: long long for С/С++, int64 for Delphi and long for Java.

Input

The only line of the input data contains three integers n, m, t (4 ≤ n ≤ 30, 1 ≤ m ≤ 30, 5 ≤ t ≤ n + m).

Output

Find the required number of ways.

Please do not use the %lld specificator to read or write 64-bit integers in С++. It is preferred to use cin, cout streams or the %I64d specificator.

Examples

Input

5 2 5


Output

10


Input

4 3 5


Output

3
class sumWrap(object):
    def __init__(self, val):
        self.sum = val

def myPrint(string):
    #print(string)
    return

def factorial(N):
    if (N == 0 or N == 1):
        return 1
    result = 1;
    for i in range(2, N + 1):
        result = result * i
    return result

def combinari(n, k):
    rez = 1
    x = 1
    while x <= k:
        rez = rez * n
        rez = int (rez / x + 0.5)
        x = x + 1
        n = n - 1
        
    return rez


total = 0
strInput = input().split(" ")
n = int(strInput[0])
m = int(strInput[1])
t = int(strInput[2])

maxGirls = t - 4
if ( m < maxGirls):
    maxGirls = m

moreOptions = True
if (m + n == t):
    total = 1
    moreOptions = False

if m < 1 or n < 4 or t < 5:
    total = 0
    moreOptions = False

if moreOptions:
    while maxGirls >= 1 and (t - maxGirls) >= 4:
        sumGirls = combinari(m, maxGirls)
        #sumGirls = factorial(m) / (factorial(m - maxGirls) * factorial(maxGirls))
        sumBoys = combinari(n, t - maxGirls)
        #sumBoys = factorial(n) / (factorial(n - t + maxGirls) * factorial(t-maxGirls))
        #total = total + factorial(m) * factorial(n) / ((factorial(n - t + maxGirls) * factorial(t-maxGirls)) * (factorial(m - maxGirls) * factorial(maxGirls)))
        total =  total + int(sumGirls) * int(sumBoys)
        maxGirls = maxGirls - 1

print(str(total))

#118264581548187697
