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 functools import reduce
import os
import sys
from collections import *
from decimal import *
from math import *
from bisect import *
from heapq import *
from io import BytesIO, IOBase

input = lambda: sys.stdin.readline().rstrip("\r\n")
def value(): return tuple(map(int, input().split())) # multiple values
def arr(): return [int(i) for i in input().split()] # aay input
def sarr(): return [str(i) for i in input()] #aay from string
def starr(): return [str(x) for x in input().split()] #string aay
def inn(): return int(input()) # integer input
def svalue(): return tuple(map(str, input().split())) #multiple string values
def parr(): return [(value()) for i in range(n)] # aay of pairs
def Ceil(a,b): return a//b+int(a%b>0)
albhabet="abcdefghijklmnopqrstuvwxyz"
mo = 1000000007
inf=1e18
div=998244353
#print("Case #{}:".format(_+1),end=" ")
#print("Case #",z+1,":",sep="",end=" ")
# ----------------------------CODE------------------------------#
n,m,k=value()
fact=[1]
val=1
for i in range(1,31):
    val*=i
    fact.append(val)

ans=0
for i in range(4,min(n+1,k)):
    for j in range(1,min(m+1,k-3)):
        if(i+j==k):
            val1=fact[n]/(fact[i]*fact[n-i])
            val2=fact[m]/(fact[j]*fact[m-j])
            ans+=int(val1)*int(val2)

print(ans)