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
# -*- coding: utf-8 -*-
"""
Spyder Editor

This temporary script file is located here:
/home/zangetsu/.spyder2/.temp.py
"""

from __future__ import division;
from bisect import *;
from fractions import Fraction;
import sys;
from math import *;
from fractions import *;
import io;
import re;

INF = 987654321987654321987654321;

def readint(delimiter=' ') :
    return map(int, raw_input().split(delimiter));

def readstr(delimiter=' ') :
    return raw_input().split(delimiter);

def readfloat(delimiter=' ') :
    return map(float, raw_input().split(delimiter));

def index(a, x):
    'Locate the leftmost value exactly equal to x'
    i = bisect_left(a, x)
    if i != len(a) and a[i] == x:
        return i
    raise ValueError

def find_lt(a, x):
    'Find rightmost value less than x'
    i = bisect_left(a, x)
    if i:
        return a[i-1]
    raise ValueError

def find_le(a, x):
    'Find rightmost value less than or equal to x'
    i = bisect_right(a, x)
    if i:
        return a[i-1]
    raise ValueError

def find_gt(a, x):
    'Find leftmost value greater than x'
    i = bisect_right(a, x)
    if i != len(a):
        return a[i]
    raise ValueError

def find_ge(a, x):
    'Find leftmost item greater than or equal to x'
    i = bisect_left(a, x)
    if i != len(a):
        return a[i]
    raise ValueError

def bin_search(a, x, left, right) :

    while left<=right :
        mid = (left + right)//2;
        
        if a[mid] == x :
            return mid;
        elif a[mid] < x :
            left = mid + 1; 
        elif a[mid] > x :
            right = mid - 1;
                       
        pass
    
    return -1;
    pass

def printf(format, *args):
    """Format args with the first argument as format string, and write.
    Return the last arg, or format itself if there are no args."""
    sys.stdout.write(str(format) % args)
    pass

if __name__ == '__main__':
    
    n, m, t = readint();    
    
    dp = [[0 for _ in xrange(33)] for _ in xrange(33)];
    dp[0][0] = 1;
    result = 0;
    for ii in xrange(1,33) :
        for jj in xrange(1, ii+1) : 
            dp[ii][jj] = dp[ii-1][jj-1] + dp[ii-1][jj];
    
    for ii in xrange(4,n+1) :
        for jj in xrange(1, m+1) :
            if ii+jj==t :
                
                result += dp[n+1][ii+1] * dp[m+1][jj+1];            
                break;
            
        pass
    
    print int(result);
    
    pass