#include <bits/stdc++.h>

using namespace std;

#define forit(it, s) for(__typeof(s.begin()) it = s.begin(); it != s.end(); it++)
#define np(v) next_permutation(v.begin(), v.end())
#define pll pair < long long, long long>
#define all(a) a.begin(), a.end()
#define ull unsigned long long
#define pii pair < ll, ll >
#define sz(a) (int)a.size()
#define sqr(x) ((x) * (x))
#define y1 stupid_cmath
#define vi vector <int>
#define pb push_back
#define mp make_pair
#define ll long long
#define endl "\n"
#define s second
#define f first
#define tm asdasd


const int inf = (int)1e9;
const int mod = (int)1e9 + 7;
const int N = (1 << 20) + 1;
const double eps = 1e-9;
const double pi = acos(-1.0);

ull n, a, b, dp[111][111];

ull calc(int n, int k){
    if(k == 0 || k == n) return 1;
    ull &res = dp[n][k];
    if(res != -1) return res;
    return res = calc(n - 1, k) + calc(n - 1, k - 1);
}

int main(){
    ios_base::sync_with_stdio(0), cin.tie(0);
    cin >> n >> a >> b;
    memset(dp, -1, sizeof dp);
    ull x = calc(n + a, a);
    ull y = calc(n + b, b);
    cout << x * y << endl;
}