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
from sys import stdin,stdout,setrecursionlimit,maxint
setrecursionlimit(2*10**5)
def listInput():
 return map(long,stdin.readline().split())
def printBS(li):
 for i in xrange(len(li)-1):
  stdout.write("%d "%li[i])
 stdout.write("%d\n"%li[-1])
def sin(): return stdin.readline().rstrip()
#n boys , m girls
# need t actors
#a+b=t
#4<=a<=n
#1<=b<=m
def ncr(n,r):
 r=min(n-r,r)
 if r==0: return 1
 if r==1: return n
 num=1
 denom=1
 for i in xrange(1,r+1):
  num*=(n-i+1)
  denom*=i
 return num/denom
#print ncr(6,3)
n,m,t=listInput()
ways=0
for a in xrange(4,n+1):
 for b in xrange(1,m+1):
  if a+b==t:
   #print a,b
   ways+=ncr(n,a)*ncr(m,b)
print ways
#5 2 6