static final long MOD = 1000000007;

    public void solve () throws Exception {
        int n = nextInt();
        int t = nextInt();

        long c [][] = new long [n + 1][n + 1];
        for (int i = 0; i <= n; i++) {
            c[i][0] = c[i][i] = 1;
            for (int j = 1; j < i; j++) {
                c[i][j] = (c[i - 1][j - 1] + c[i - 1][j]) % MOD;
            }
        }

        int a [] = new int [n];
        int count [] = new int [5001];
        for (int i = 0; i < n; i++) {
            a [i] = nextInt();
            count [a[i]]++;
        }
        int p = a[nextInt() - 1];
        int pos = nextInt();

        int pleft = pos - 1;
        int pright = t - pos;

        int countLeft = 0;
        int countRight = 0;

        for (int i = 0; i < p; i++) {
            countLeft += count [i];
        }
        for (int i = p + 1; i <= 5000; i++) {
            countRight += count [i];
        }

        long answer = 0;

        for (int left = 0; left <= count [p] - 1; left++) {
            for (int right = 0; right + left <= count [p] - 1 && left <= pleft && right <= pright; right++) {
                long cur = c[count[p] - 1][left + right];
                long la = (c[countLeft][pleft - left]) % MOD;
                cur = (cur * la) % MOD;
                long ra = (c[countRight][pright - right]) % MOD;
                cur = (cur * ra) % MOD;
                answer = (answer + cur) % MOD;
            }
        }

        out.println(answer);
    }