#include <bits/stdc++.h>
using namespace std;

typedef long long ll;
typedef unsigned long long ull;
typedef pair<ll, ll> P;

#define fi first
#define se second
#define repl(i,a,b) for(ll i=(ll)(a);i<(ll)(b);i++)
#define rep(i,n) repl(i,0,n)
#define all(x) (x).begin(),(x).end()
#define dbg(x) cout<<#x"="<<x<<endl
#define mmax(x,y) (x>y?x:y)
#define mmin(x,y) (x<y?x:y)
#define maxch(x,y) x=mmax(x,y)
#define minch(x,y) x=mmin(x,y)
#define uni(x) x.erase(unique(all(x)),x.end())
#define exist(x,y) (find(all(x),y)!=x.end())
#define bcnt __builtin_popcountll

#define INF 1e16
#define mod 1000000007

ll N,S,K;
ll dp[101][20001];

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

  cin>>N>>S>>K;
  S-=K*(N*(N-1)/2);
  if(S<0){
    cout<<0<<endl;
    return 0;
  }

  dp[0][0]=1;
  rep(i,N)rep(j,S+1){
    if(j-i-1>=0) (dp[i+1][j]+=dp[i+1][j-i-1]+dp[i][j])%=mod;
    else (dp[i+1][j]+=dp[i][j])%=mod;
  }
  cout<<dp[N][S]<<endl;

  return 0;
}