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
import sys
import string
import math
from collections import defaultdict
from functools import lru_cache
from collections import Counter
from fractions import Fraction

def mi(s):
    return map(int, s.strip().split())

def lmi(s):
    return list(mi(s))

def tmi(s):
    return tuple(mi(s))

def mf(f, s):
    return map(f, s)

def lmf(f, s):
    return list(mf(f, s))

def js(lst):
    return " ".join(str(d) for d in lst)

def jsns(lst):
    return "".join(str(d) for d in lst)

def line():
    return sys.stdin.readline().strip()

def linesp():
    return line().split()

def iline():
    return int(line())

def mat(n):
    matr = []
    for _ in range(n):
        matr.append(linesp())
    return matr

def matns(n):
    mat = []
    for _ in range(n):
        mat.append([c for c in line()])
    return mat

def mati(n):
    mat = []
    for _ in range(n):
       mat.append(lmi(line())) 
    return mat

def pmat(mat):
    for row in mat:
        print(js(row))

def factorial(n):
    ans = 1
    for i in range(1, n + 1):
        ans *= i
    return ans

def nchoosek(n, k):
    if n <= 0 and k > 0:
        return 0
    elif n <= 0 and k <= 0:
        return 1

    return factorial(n) // (factorial(n - k) * factorial(k))

def main():
    n, m, t = mi(line())

    s = 0
    for boys in range(4, t):
        girls = t - boys
        s += nchoosek(n, boys) * nchoosek(m, girls)
    print(s)
main()
