use std::io::*;
use std::str::FromStr;

#[allow(dead_code)]
fn read<T: FromStr>() -> T {
    let stdin = stdin();
    let stdin = stdin.lock();
    let token: String = stdin
        .bytes()
        .map(|c| c.expect("failed to read char") as char)
        .skip_while(|c| c.is_whitespace())
        .take_while(|c| !c.is_whitespace())
        .collect();
    token.parse().ok().expect("failed to parse token")
}

type Weight = i32;
#[allow(dead_code)]
#[derive(Clone, Debug, Eq, PartialEq)]
struct Edge {
    index: usize,
    src: usize,
    dest: usize,
    weight: Weight,
}
#[allow(dead_code)]
impl Edge {
    fn new(index: usize, src: usize, dest: usize, weight: Weight) -> Edge {
        Edge {
            index: index,
            src: src,
            dest: dest,
            weight: weight,
        }
    }
}
impl std::cmp::Ord for Edge {
    fn cmp(&self, other: &Self) -> std::cmp::Ordering {
        (self.weight, self.src, self.dest).cmp(&(other.weight, other.src, other.dest))
    }
}
impl std::cmp::PartialOrd for Edge {
    fn partial_cmp(&self, other: &Self) -> Option<std::cmp::Ordering> {
        Some(self.cmp(other))
    }
}
type Edges = Vec<Edge>;
type Graph = Vec<Edges>;
#[allow(dead_code)]
fn graph_new(n: usize) -> Graph {
    vec![vec![]; n]
}
#[allow(dead_code)]
fn add_bi_edge(graph: &mut Graph, index: &mut usize, src: usize, dest: usize, weight: Weight) {
    graph[src].push(Edge::new(*index, src, dest, weight));
    graph[dest].push(Edge::new(*index, dest, src, weight));
    *index += 1;
}
#[allow(dead_code)]
fn add_uni_edge(graph: &mut Graph, index: &mut usize, src: usize, dest: usize, weight: Weight) {
    graph[src].push(Edge::new(*index, src, dest, weight));
    *index += 1;
}

#[allow(dead_code)]
fn pow_mod(base: i64, power: i64, modulo: i64) -> i64 {
    let mut base = base;
    let mut power = power;
    let mut ans = 1;
    while power > 0 {
        if power & 1 == 1 {
            ans = ans * base % modulo;
        }
        power >>= 1;
        base = base * base % modulo;
    }
    ans
}

#[allow(dead_code)]
fn inv_mod(a: i64, modulo: i64) -> i64 {
    pow_mod(a, modulo - 2, modulo)
}

const MOD: i64 = 1e+9 as i64 + 7;
const FACT_MAX: usize = 100010;
static mut FACTORIAL: [i64; FACT_MAX + 1] = [0; FACT_MAX + 1];
static mut RFACTORIAL: [i64; FACT_MAX + 1] = [0; FACT_MAX + 1];
fn init_fact() {
    unsafe {
        if FACTORIAL[0] == 0 {
            FACTORIAL[0] = 1;
            for i in 1..FACT_MAX + 1 {
                FACTORIAL[i] = (FACTORIAL[i - 1] * i as i64) % MOD;
            }
            RFACTORIAL[FACT_MAX] = inv_mod(FACTORIAL[FACT_MAX], MOD);
            for i in (0..FACT_MAX).rev() {
                RFACTORIAL[i] = RFACTORIAL[i + 1] * (i as i64 + 1) % MOD;
            }
        }
    }
}
#[allow(dead_code)]
fn fact(n: usize) -> i64 {
    init_fact();
    unsafe { FACTORIAL[n] }
}
#[allow(dead_code, unused_comparisons)]
fn combi(n: usize, m: usize) -> i64 {
    if n < m || m < 0 {
        return 0;
    }
    init_fact();
    unsafe { FACTORIAL[n] * RFACTORIAL[m] % MOD * RFACTORIAL[n - m] % MOD }
}


fn dfs(from: usize, parent: usize, k: i64, g: &Graph) -> i64 {
    let mut ret = 1;
    let mut cnt = 0;
    for e in g[from].iter() {
        if e.dest == parent {
            continue;
        }
        let mut nret = dfs(e.dest, from, k, g);
        ret = ret * nret % MOD;
        cnt += 1;
    }
    let parent_cnt = if from == parent { 0 } else { 1 };
    if cnt + 1 + parent_cnt > k {
        return 0;
    }
    ret = ret * combi((k - 1 - parent_cnt) as usize, cnt as usize) % MOD * fact(cnt as usize) % MOD;
    return ret;
}

fn main() {
    let n = read::<usize>();
    let k = read::<i64>();
    let mut g = graph_new(n);
    let mut index = 0;
    for _i in 0..n - 1 {
        let f = read::<usize>() - 1;
        let t = read::<usize>() - 1;
        add_bi_edge(&mut g, &mut index, f, t, 1);
    }
    let ans = dfs(0, 0, k, &g) * k % MOD;
    println!("{}", ans);
}


Measured memory_bytes: 28156