#include <cstdio>
#include <iostream>
#include <sstream>
#include <fstream>
#include <iomanip>
#include <algorithm>
#include <cmath>
#include <string>
#include <vector>
#include <list>
#include <queue>
#include <stack>
#include <set>
#include <map>
#include <bitset>
#include <numeric>
#include <limits>
#include <climits>
#include <cfloat>
#include <functional>
using namespace std;

const int MOD = 1000000007;

int main()
{
    int n, s, d;
    cin >> n >> s >> d;
    s -= n * (n - 1) / 2 * d;
    if(s < 0){
        cout << 0 << endl;
        return 0;
    }

    vector<int> dp(s+1, 0);
    dp[0] = 1;
    for(int i=0; i<n; ++i){
        for(int j=0; j<=s; ++j){
            int a = j + (n - i);
            if(s < a)
                break;
            dp[a] += dp[j];
            dp[a] %= MOD;
        }
    }
    cout << dp[s] << endl;

    return 0;
}