#include <iostream>
#include <cstring>
using namespace std;
typedef long long ll;
const int maxn = 105;
int n, m, k;
ll dp[maxn][maxn];
ll rec(int food, int rooms) {
    if(food == n and rooms == k) {
        return 1;
    }

    if(dp[food][rooms] != -1) {
        return dp[food][rooms];
    }
    ll res = 0;
    for(int i = 1; i <= m; i++) {
        if(food + i <= n) {
            res += rec(food + i, rooms + 1);
        }
    }

    dp[food][rooms] = res;
    return res;
}
int main() {
    ios_base::sync_with_stdio(false);
    memset(dp, -1, sizeof dp);
    cin >> n >> k >> m;

    cout << rec(0, 0) << endl;

    return 0;
}