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;
}
1654C - Alice and the Cake | 369A - Valera and Plates |
1626A - Equidistant Letters | 977D - Divide by three multiply by two |
1654B - Prefix Removals | 1654A - Maximum Cake Tastiness |
1649A - Game | 139A - Petr and Book |
1612A - Distance | 520A - Pangram |
124A - The number of positions | 1041A - Heist |
901A - Hashing Trees | 1283A - Minutes Before the New Year |
1654D - Potion Brewing Class | 1107B - Digital root |
25A - IQ test | 785A - Anton and Polyhedrons |
1542B - Plus and Multiply | 306A - Candies |
1651C - Fault-tolerant Network | 870A - Search for Pretty Integers |
1174A - Ehab Fails to Be Thanos | 1169A - Circle Metro |
780C - Andryusha and Colored Balloons | 1153A - Serval and Bus |
1487C - Minimum Ties | 1136A - Nastya Is Reading a Book |
1353B - Two Arrays And Swaps | 1490E - Accidental Victory |