#include <bits/stdc++.h>
using namespace std;
typedef long long ll;
#define rep(i, n) for(ll i = 0; i < n; i++)
#define FOR(i, m, n) for(ll i = m; i < n; i++)
#define all(vec) vec.begin(), vec.end()
#define tmax(x, y, z) max((x), max((y), (z)))
#define tmin(x, y, z) min((x), min((y), (z)))
#define MINUS(a) memset(a, 0xff, sizeof(a))
#define ZERO(a) memset(a, 0, sizeof(a))
const ll INF = 1LL << 60;
ll MM = 1000000000; const ll MOD = MM + 7; ll MMM=9223372036854775807;//2^63 -1
#define ADD(a,b) a = (a + ll(b)) % MOD
#define MUL(a,b) a = (a * ll(b)) % MOD
ll GCD(ll x, ll y){ if(y == 0) return x; else return GCD(y, x % y);}
ll LCM(ll x, ll y){ return x / GCD(x, y) * y;}
template<class T> inline bool chmin(T& a, T b){ if(a > b){ a = b; return true;} return false;}
template<class T> inline bool chmax(T& a, T b){ if(a < b){ a = b; return true;} return false;}
template<typename A, size_t N, typename T> void FILL(A (&array)[N], const T &val){ fill( (T*)array, (T*)(array+N), val );}
using Graph = vector<vector<ll>>;
int dx[4] = {1, 0, -1, 0}, dy[4] = {0, 1, 0, -1};
int ddx[8] = {1, 1, 0, -1, -1, -1, 0, 1}, ddy[8] = {0, 1, 1, 1, 0, -1, -1, -1};
//cout << fixed << setprecision(10);

ll dp[101][20001];


int main() {
    ll n, s, k;
    cin >> n >> s >> k;
    ll bun = s - (n-1)*n/2*k;

    dp[0][0] = 1;
    FOR(i, 1, n+1){
        rep(j, bun+1){
            if(j - i >= 0) dp[i][j] = (dp[i][j-i] + dp[i-1][j]) % MOD;
            else dp[i][j] = dp[i-1][j];
        }
    }

    cout << dp[n][bun] << endl;;
}