#include <iostream>
#include <iomanip>
#include <vector>
#include <stack>
#include <queue>
#include <set>
#include <map>
#include <algorithm>
#include <cstdio>
#include <utility>
#include <string>
#include <cmath>
#include <cstdlib>
#include <cstring>
#include <deque>
#include <numeric>

using namespace std;

typedef uint64_t u64;
typedef int64_t s64;
typedef uint32_t u32;
typedef int32_t s32;
typedef vector<s32> vs32;
typedef vector<u32> vu32;
typedef vector<s64> vs64;
typedef vector<u64> vu64;

const double PI=3.14159265358979323846;

#define MAX(x, y) ((x) < (y) ? (y) : (x))
#define MIN(x, y) ((x) > (y) ? (y) : (x))

#define rep(i, N) for(int i = 0; i < N; ++i)

#define CEIL(x, y) (((x) + (y) - 1) / (y))
#define MOD 1000000007ULL

#define IN(l, r, x) ((l) <= (x) && (x) < (r))

int main()
{
    cin.tie(0);
    ios::sync_with_stdio(false);

    int n, s, k;
    cin >> n >> s >> k;

    if (s < n * (n - 1) * k / 2)
    {
        cout << "0\n";
        return 0;
    }

    int m = s - n * (n - 1) * k / 2;
    cout << "m = " << m << "\n";
    s64 dp[n + 1][m + 1];
    rep (i, n + 1) rep (j, m + 1) dp[i][j] = 0;
    dp[0][0] = 1;
    for (int i = 1; i <= n; ++i)
    {
        rep (j, m + 1)
        {
            if (j - i >= 0) dp[i][j] = (dp[i][j - i] + dp[i - 1][j]) % MOD;
            else dp[i][j] = dp[i - 1][j];
        }
    }

    cout << dp[n][m] << "\n";
    return 0;
}