#include <bits/stdc++.h>

#define int             long long
#define FOR( i, m, n )  for( int (i) = (m); (i) < (n); (i)++ )
#define REP( i, n )     FOR( i, 0, n )
#define REPR( i, m )    for( int (i) = (m); (i) >= 0; (i)-- )
#define ALL( a )        (a).begin(), (a).end()
#define MP              make_pair

using namespace std;
using P = pair<int, int>;

template<class T>bool chmax( T& a, const T& b ) { if( a < b ) { a = b; return 1; } return 0; }
template<class T>bool chmin( T& a, const T& b ) { if( a > b ) { a = b; return 1; } return 0; }

const int INF = 1e18;
const int MOD = 1e9 + 7;

int dp[101][20001];

signed main(){
    int N, S, K; cin >> N >> S >> K;
    FOR( i, 1, N ){
        S -= i * K;
    }

    dp[0][0] = 1;
    FOR( i, 1, N + 1 ){
        REP( j, S + 1 ){
            if( j - i >= 0 ){
                dp[i][j] = ( dp[i - 1][j] + dp[i][j - i] ) % MOD;
            }else{
                dp[i][j] = dp[i - 1][j];
            }
        }
    }

    cout << dp[N][S] << endl;
}