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

#some convinient function

def make_primelist(size):
  global prime
  from math import sqrt
  _prime=[1 for i in xrange(size+1)]
  _prime[0]=0
  _prime[1]=0
  for i in xrange(size):
    if i*i>size:
      break
    if _prime[i]==0:
      continue
    for k in xrange(2*i,size+1,i):
      _prime[k]=0
  prime=_prime

choice_max=2000
dp_choice=[[None for i in xrange(choice_max+1)] for j in xrange(choice_max+1)]
def choice(n,m): #return (n+m)!/(n!m!)
  if n<0 or m<0:
    return 0
  if dp_choice[n][m]!=None:
    return dp_choice[n][m]
  if n==m==0:
    ret=1
  else:
    ret=choice(n-1,m)+choice(n,m-1)
  dp_choice[n][m]=ret
  return ret

def inverse(x,M): #1/x mod m
  x=x%M
  if x==0 or M<=0:
    raise
  a,b,c,d=1,0,0,1
  v1,v2=x,M
  while v2:
    n=v1/v2
    v1,v2=v2,v1-n*v2
    a, b, c, d = c, d, a-n*c, b-n*d
  if v1!=1:
    raise
  return a%M

def div(a,b,M):
  return a*inverse(b,M)%M

def gcd(x,y):
  while y:
    x,y=y,x%y
  return x

"""
example
choice(0,5)==1 and choice(1,4)==5 and choice(2,3)==10
make_primelist(6); prime==[0,0,1,1,0,1,0]
inverse(3,10) == 7
div(7,9,10) == 3  because 27/9==3
gcd(10,15) == 5
"""



def readints():
  return map(int,raw_input().split())

def main():
  n,m,t=readints()
  ret = 0
  for k in xrange(4,n+1):
    a,b=k,t-k
    if b<1:continue
    ret += choice(n-a,a) * choice(m-b,b)
  print ret
  pass



if __name__=='__main__':
  main()


