def recur_factorial(n, end):
if n < 1 or end >= n:
return 1
else:
return n*recur_factorial(n-1, end)
n, m, t = list(map(int, input().split()))
x = 0
for i in range(4, t):
comb1 = recur_factorial(n, n - i) / recur_factorial(i, 1)
comb2 = recur_factorial(m, m - (t - i)) / recur_factorial(t - i, 1)
x += (int(comb1) * int(comb2))
print(x)#include<bits/stdc++.h>
using namespace std;
long long ans;
int n,m,t;
long long C(int n,int k){
long long f=1;
for(int i=0;i<k;i++)f*=n-i,f/=i+1;
return f;
}
main(){
cin>>n>>m>>t;
for(int i=4;i<=n&&i<t;i++){
ans+=C(n,i)*C(m,t-i);
}
cout<<ans;
}
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1430C - Numbers on Whiteboard | 1697B - Promo |
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1512B - Almost Rectangle | 831B - Keyboard Layouts |
814A - An abandoned sentiment from past | 268C - Beautiful Sets of Points |
1391C - Cyclic Permutations | 11A - Increasing Sequence |
1406A - Subset Mex | 1365F - Swaps Again |
50B - Choosing Symbol Pairs | 1719A - Chip Game |
454B - Little Pony and Sort by Shift | 1152A - Neko Finds Grapes |
1719B - Mathematical Circus | 1719C - Fighting Tournament |
1642A - Hard Way | 285C - Building Permutation |
1719E - Fibonacci Strings | 1696C - Fishingprince Plays With Array |
1085A - Right-Left Cipher | 1508B - Almost Sorted |