sequences

#include <iostream>
using namespace std;

const int N=101;
long long int dp[N][N];
long long int sum[N][N];

int n,m,k;

int main()
{
  cin >> n >> m >> k;

 for (int i = 1; i < n + 1; i++)
    {
        dp[0][i] = 0;
        sum[0][i] = 1;
    }

 for (int i = 0; i < m + 1; i++) sum[i][0] = dp[i][0] = 1;

 for (int i = 1; i < m + 1; i++)
 {
   for (int j = 1; j < n + 1; j++)
    {
      dp[i][j] = sum[i - 1][j];
      if (j > k) dp[i][j] -= sum[i - 1][j - k - 1];

    }
    for (int j = 1; j < n + 1; j++)
      sum[i][j] = dp[i][j] + sum[i][j - 1];
 }
 cout << dp[m][n] << endl;
}