#include <bits/stdc++.h>
#define REP(i,a,b) for (int i=(a);i<(b);++i)
#define rep(i,n) REP(i,0,n)
#define sz(x) (x).size()
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef pair<ll,ll> pll;
const int INF = 1e9;
const ll LINF = 1LL<<60;
const ll MOD = 1e9+7;
template<class T> inline bool chmax(T& a, T b) { if (a < b) { a = b; return true; } return false; }
template<class T> inline bool chmin(T& a, T b) { if (a > b) { a = b; return true; } return false; }

ll n,s,k,dp[101][20001];

int main() {
  cin>>n>>s>>k;
  ll ks = 0;
  rep(i,n) ks += k*i;
  if (ks > s) {
    cout << 0 << '\n';
    return 0;
  }
  ll r = s-ks;
  dp[0][0] = 1;
  REP(i,1,n+1) {
    rep(j,r+1) {
      if (j-i >= 0) dp[i][j] = (dp[i][j-i]%MOD+dp[i-1][j]%MOD)%MOD;
      else dp[i][j] = dp[i-1][j]%MOD;
    }
  }
  cout << dp[n][r] << '\n';
  return 0;
}