#include <bits/stdc++.h>
#define MOD 1000000007
int ri() {
	int n;
	scanf("%d", &n);
	return n;
}
int64_t rll() {
	long long n;
	scanf("%lld", &n);
	return n;
}

template<int mod>
struct ModInt{
    int x;
    ModInt():x(0){}
    ModInt(long long y):x(y>=0?y%mod:(mod-(-y)%mod)%mod){}
    ModInt &operator+=(const ModInt &p){
        if((x+=p.x)>=mod)x-=mod;
        return *this;
    }
    ModInt &operator-=(const ModInt &p){
        if((x+=mod-p.x)>=mod)x-=mod;
        return *this;
    }
    ModInt &operator*=(const ModInt &p){
        x=(int)(1LL*x*p.x%mod);
        return *this;
    }
    ModInt &operator/=(const ModInt &p){
        *this*=p.inverse();
        return *this;
    }
	ModInt &operator^=(long long p){
		ModInt res = 1;
		for (; p; p >>= 1) {
			if (p & 1) res *= *this;
			*this *= *this;
		}
		return *this = res;
	}
    ModInt operator-()const{return ModInt(-x);}
    ModInt operator+(const ModInt &p)const{return ModInt(*this)+=p;}
    ModInt operator-(const ModInt &p)const{return ModInt(*this)-=p;}
    ModInt operator*(const ModInt &p)const{return ModInt(*this)*=p;}
    ModInt operator/(const ModInt &p)const{return ModInt(*this)/=p;}
	ModInt operator^(long long p)const{return ModInt(*this)^=p;}
    bool operator==(const ModInt &p)const{return x==p.x;}
    bool operator!=(const ModInt &p)const{return x!=p.x;}
    explicit operator int() const { return x; }                           // added by QCFium
    ModInt operator=(const int p) {x = p; return ModInt(*this);} // added by QCFium
    ModInt inverse()const{
        int a=x,b=mod,u=1,v=0,t;
        while(b>0){
            t=a/b;
            a-=t*b;
            std::swap(a,b);
            u-=t*v;
            std::swap(u,v);
        }
        return ModInt(u);
    }
    friend std::ostream &operator<<(std::ostream &os,const ModInt<mod> &p){
        return os<<p.x;
    }
    friend std::istream &operator>>(std::istream &is,ModInt<mod> &a){
        long long x;
        is>>x;
        a=ModInt<mod>(x);
        return (is);
    }
};
typedef ModInt<MOD> mint;

struct MComb {
    std::vector<mint> fact;
    std::vector<mint> inversed;
    MComb(int n) { // O(n+log(mod))
        fact = std::vector<mint>(n+1,1);
        for (int i = 1; i <= n; i++) fact[i] = fact[i-1]*mint(i);
        inversed = std::vector<mint>(n+1);
        inversed[n] = fact[n] ^ (MOD-2);
        for (int i = n - 1; i >= 0; i--) inversed[i]=inversed[i+1]*mint(i+1);
    }
    mint ncr(int n, int r) {
        return (fact[n] * inversed[r] * inversed[n-r]);
    }
    mint npr(int n, int r) {
        return (fact[n] * inversed[n-r]);
    }
    mint nhr(int n, int r) {
        assert(n+r-1 < (int)fact.size());
        return ncr(n+r-1, r);
    }
};

int main() {
	int n = ri(), k = ri();
	int a[n - 1], b[n - 1];
	std::vector<std::set<int> > hen(n);
	for (int i = 0; i + 1 < n; i++) {
		a[i] = ri() - 1, b[i] = ri() - 1;
		hen[a[i]].insert(b[i]);
		hen[b[i]].insert(a[i]);
	}
	int depth[n];
	std::fill(depth, depth + n, -1);
	std::queue<int> que;
	depth[0] = 0;
	que.push(0);
	MComb com(100001);
	while (que.size()) {
		int x = que.front();
		que.pop();
		std::set<int> next;
		for (auto i : hen[x]) {
			if (depth[i] != -1) continue;
			depth[i] = depth[x] + 1;
			que.push(i);
			next.insert(i);
		}
		std::swap(next, hen[x]);
	}
	std::vector<std::pair<int, int> > all;
	for (int i = 0; i < n; i++) all.push_back({depth[i], i});
	std::sort(all.begin(), all.end(), std::greater<>());
	std::vector<mint> prod(n);
	for (int i = 0; i < n; i++) {
		int child_num = hen[i].size();
		if (!child_num) prod[i] = 1;
		else {
			int colors = k - 1;
			if (i) colors--;
			if (colors < child_num) prod[i] = 0;
			else prod[i] = com.npr(colors, child_num);
		}
	}
	mint res = k;
	for (int i = 0; i < n; i++) res *= prod[i];
	std::cout << res << std::endl;
	return 0;
}


Measured memory_bytes: 21376