#include <bits/stdc++.h>
using namespace std;
#define fastio cin.tie(0) -> sync_with_stdio(0) 

//jiangly Codeforces
int P = 1e9+7;
using i64 = long long;
// assume -P <= x < 2P
int norm(int x) {
    if (x < 0) {
        x += P;
    }
    if (x >= P) {
        x -= P;
    }
    return x;
}
template<class T>
T power(T a, i64 b) {
    T res = 1;
    for (; b; b /= 2, a *= a) {
        if (b % 2) {
            res *= a;
        }
    }
    return res;
}
struct Z {
    int x;
    Z(int x = 0) : x(norm(x)) {}
    Z(i64 x) : x(norm((int)(x % P))) {}
    int val() const {
        return x;
    }
    Z operator-() const {
        return Z(norm(P - x));
    }
    Z inv() const {
        assert(x != 0);
        return power(*this, P - 2);
    }
    Z &operator*=(const Z &rhs) {
        x = i64(x) * rhs.x % P;
        return *this;
    }
    Z &operator+=(const Z &rhs) {
        x = norm(x + rhs.x);
        return *this;
    }
    Z &operator-=(const Z &rhs) {
        x = norm(x - rhs.x);
        return *this;
    }
    Z &operator/=(const Z &rhs) {
        return *this *= rhs.inv();
    }
    friend Z operator*(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res *= rhs;
        return res;
    }
    friend Z operator+(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res += rhs;
        return res;
    }
    friend Z operator-(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res -= rhs;
        return res;
    }
    friend Z operator/(const Z &lhs, const Z &rhs) {
        Z res = lhs;
        res /= rhs;
        return res;
    }
    friend std::istream &operator>>(std::istream &is, Z &a) {
        i64 v;
        is >> v;
        a = Z(v);
        return is;
    }
    friend std::ostream &operator<<(std::ostream &os, const Z &a) {
        return os << a.val();
    }
};

#define DEBUG 0

void debug(const char* p){
    #if DEBUG
    freopen(p, "r", stdin); 
    #else
    fastio;
    #endif      
}

int main(void){
    debug("test1.txt");
    int n, m, v;
    cin >> n >> m >> v;
    Z zv = Z(v);
    vector<Z> a(n+1);
    for(int i = 1; i <= n; ++i) cin >> a[i];
    vector<vector<Z>> dp(n+1, vector<Z>(min(n, m)+1));
    dp[0][0] = 1;
    Z invn = Z(n).inv(), ans = 0;
    for(int r = 0; r < n; ++r){
        for(int s = 0; s <= r && s <= m; ++s){
            dp[r+1][s] += (a[r+1] + zv * s) * dp[r][s];
            if(s < m) dp[r+1][s+1] += Z(r+1) * invn * zv * Z(m - s) * dp[r][s];
        }
    }
    for(int s = 0; s <= min(n, m); ++s) ans += dp[n][s];
    cout << ans << "\n";
}