#include<iostream>
#include<string>
#include<cstring>
#include <cstdio>
#include<utility>
#include<algorithm>
#include<vector>
#include<cmath>
#include<map>
#include<bitset>
#include<queue>
#include<stack>
#include<set>
#include <limits>
#include <climits>
#include <numeric>
#include <cassert>
#include <algorithm>
#include <functional>
using namespace std;
typedef long long ll;
typedef vector<int>VI;
typedef pair<int,int>P;
typedef pair<double,double>P_D;
//const int dx[4]={1,0,-1,0},dy[4]={0,1,0,-1};
#define PI 3.1415926535897932384626433832795
#define rep(i, n) for (ll i = 0; i < (ll)n; i++)
#define reprev(i, n) for (ll i = (ll)n - 1; i >= 0; i--)
#define ALL(a)  (a).begin(),(a).end()
#define C_MAX(a, b) ((a)>(b)?(a):(b))
#define fi first
#define se second
#define MAX 100100//5
#define MAX_N 200100
#define MAX_B 1001001//6
#define MAX_S 10010010//7
#define SENTINEL 2000000000//9
#define NIL -1
#define MOD 1000000007
#define INF 1 << 29
#define INFTY 1000000000000000000LL
#define MAX_INT INT_MAX
ll dp[20001][101];//dp[i][j]:=i個のj分割
int main(){
    ll n,s,k;cin>>n>>s>>k;
    ll sub=0;
    for(int i=0;i<n;i++){
        sub+=i*k;
    }
    s-=sub;
    if(s<0){cout<<0<<endl;return 0;}
    dp[0][0]=1;
    for(int i=0;i<=s;i++)
        for(int j=1;j<=n;j++){
            if(i-j>=0)dp[i][j]=(dp[i-j][j]+dp[i][j-1])%MOD;
            else dp[i][j]=dp[i][j-1]%MOD;
        }
        ll ans=dp[s][n];
        cout<<ans<<endl;
}