#pragma region template
#include<bits/stdc++.h>
using namespace std;
//other
#include <ext/pb_ds/assoc_container.hpp>
#include <ext/pb_ds/tree_policy.hpp>
using namespace __gnu_pbds;
template<class T> using pbds=tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>;
#include<atcoder/all>
using namespace atcoder;
#include "atcoder/modint.hpp"
using mint = atcoder::modint998244353;
using mint2 = atcoder::modint1000000007;
#define int long long
#define pb push_back
#define eb emplace_back
#define ep emplace
#define len(a) (int)a.size()

#pragma GCC target("avx2")
#pragma GCC optimize("O3")
#pragma GCC optimize("unroll-loops")

//using 
using ll=long long;
using ld=long double;
using ull=unsigned long long;
using uint=unsigned;
using pcc=pair<char,char>;
using pii=pair<int,int>;
using pll=pair<ll,ll>;
using pdd=pair<ld,ld>;
using vi=vector<int>;
using vl=vector<ll>;
using vvi=vector<vi>;
using vvl=vector<vl>;
using vvvi=vector<vvi>;
using vvvl=vector<vvl>;
template<class T>using pqmin=priority_queue<T,vector<T>,greater<T>>;
template<class T>using pqmax=priority_queue<T>;

const ll LINF=0x1fffffffffffffff;
const int INF=0x3fffffff;
const int MOD=998244353;
const int MOD2=1000000007;
const ld PI=3.1415926535897932384626433832795028841971;
const ld DINF=numeric_limits<ld>::infinity();
const ld EPS=1e-9;
const ll di[]={0,1,0,-1,1,-1,1,-1};
const ll dj[]={1,0,-1,0,1,1,-1,-1};

template<class T>
constexpr auto min(T a,T b,T c){
    return min(a,min(b,c));
}
template<class... T>
constexpr auto min(T... a){
    return min(initializer_list<common_type_t<T...>>{a...});
}

template<class T>
constexpr auto max(T a,T b,T c){
    return max(a,max(b,c));
}

template<class... T>
constexpr auto max(T... a){
    return max(initializer_list<common_type_t<T...>>{a...});
}

#define overload4(_1,_2,_3,_4,name,...) name
#define overload3(_1,_2,_3,name,...) name

#define rep1(n) for(ll i=0;i<n;++i)
#define rep2(i,n) for(ll i=0;i<n;++i)
#define rep3(i,a,b) for(ll i=a;i<b;++i)
#define rep4(i,a,b,c) for(ll i=a;i<b;i+=c)
#define rep(...) overload4(__VA_ARGS__,rep4,rep3,rep2,rep1)(__VA_ARGS__)

#define rrep1(n)for(ll i=n;i--;)
#define rrep2(i,n)for(ll i=n;i--;)
#define rrep3(i,a,b)for(ll i=b;i-->(a);)
#define rrep4(i,a,b,c)for(ll i=(a)+((b)-(a)-1)/(c)*(c);i>=(a);i-=c)
#define rrep(...) overload4(__VA_ARGS__,rrep4,rrep3,rrep2,rrep1)(__VA_ARGS__)

#define all1(i) begin(i),end(i)
#define all2(i,a) begin(i),begin(i)+a
#define all3(i,a,b) begin(i)+a,begin(i)+b
#define all(...) overload3(__VA_ARGS__,all3,all2,all1)(__VA_ARGS__)

#define sum(...) accumulate(all(__VA_ARGS__),0LL)
#define dsum(...) accumulate(all(__VA_ARGS__),0.0L)
#define Msum(...) accumulate(all(__VA_ARGS__),0_M)
#define elif else if

#define INT(...) int __VA_ARGS__;input(__VA_ARGS__)
#define LL(...) ll __VA_ARGS__;input(__VA_ARGS__)
#define ULL(...) ull __VA_ARGS__;input(__VA_ARGS__)
#define STR(...) string __VA_ARGS__;input(__VA_ARGS__)
#define CHR(...) char __VA_ARGS__;input(__VA_ARGS__)
#define DBL(...) double __VA_ARGS__;input(__VA_ARGS__)
#define LD(...) ld __VA_ARGS__;input(__VA_ARGS__)

int chmax(int &a,int b){
    if(a<b){a=b;return 1;}
    else return 0;
}
int chmin(int &a,int b){
    if(a>b){a=b;return 1;}
    else return 0;
}
//io
//in
void scan(){}
// void scan(int &a){cin>>a;}
void scan(unsigned &a){cin>>a;}
void scan(long& a){cin>>a;}
void scan(long long& a){cin>>a;}
void scan(unsigned long long&a){cin>>a;}
void scan(char& a){cin>>a;}
void scan(float& a){cin>>a;}
void scan(double& a){cin>>a;}
void scan(long double& a){cin>>a;}
void scan(vector<bool>& a){ for(unsigned i = 0; i < a.size(); i++){ int b; scan(b); a[i] = b; } }
void scan(char a[]){ scanf("%s", a); }
void scan(string& a){cin>>a;}
template<class T> void scan(vector<T>&);
template<class T, size_t size> void scan(array<T, size>&);
template<class T, class L> void scan(pair<T, L>&);
template<class T, size_t size> void scan(T(&)[size]);
template<class T> void scan(vector<T>& a){ for(auto&& i : a) scan(i); }
template<class T> void scan(deque<T>& a){ for(auto&& i : a) scan(i); }
template<class T, size_t size> void scan(array<T, size>& a){ for(auto&& i : a) scan(i); }
template<class T, class L> void scan(pair<T, L>& p){ scan(p.first); scan(p.second); }
template<class T, size_t size> void scan(T (&a)[size]){ for(auto&& i : a) scan(i); }
template<class T> void scan(T& a){ cin >> a; }
void input(){}
template<class Head,class...Tail> void input(Head& head,Tail&... tail){scan(head);input(tail...);}
//out
void puts(){ putchar(' '); }
void puts(bool a){ printf("%d", a); }
// void puts(int a){ printf("%d", a); }
void puts(unsigned a){ printf("%u", a); }
void puts(long a){ printf("%ld", a); }
void puts(long long a){ printf("%lld", a); }
void puts(unsigned long long a){ printf("%llu", a); }
void puts(char a){ printf("%c", a); }
void puts(char a[]){ printf("%s", a); }
// void puts(const char a[]){ printf("%s", a); }
void puts(float a){ printf("%.15f", a); }
void puts(double a){ printf("%.15f", a); }
void puts(long double a){ printf("%.15Lf", a); }
void puts(const string& a){ for(auto&& i : a) puts(i); }
template<class T> void puts(const complex<T>& a){ if(a.real() >= 0) puts('+'); puts(a.real()); if(a.imag() >= 0) puts('+'); puts(a.imag()); puts('i'); }
template<class T> void puts(const vector<T>&);
template<class T, size_t size> void puts(const array<T, size>&);
template<class T, class L> void puts(const pair<T, L>& p);
template<class T, size_t size> void puts(const T (&)[size]);
template<class T> void puts(const vector<T>& a){ if(a.empty()) return; puts(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); puts(*i); } }
template<class T> void puts(const deque<T>& a){ if(a.empty()) return; puts(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); puts(*i); } }
template<class T> void puts(const set<T>& a){ if(a.empty()) return; puts(*a.begin()); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); puts(*i); } }
template<class T> void puts(const multiset<T>& a){ if(a.empty()) return; puts(*a.begin()); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); puts(*i); } }
template<class T, size_t size> void puts(const array<T, size>& a){ puts(a[0]); for(auto i = a.begin(); ++i != a.end(); ){ putchar(' '); puts(*i); } }
template<class T, class L> void puts(const pair<T, L>& p){ puts(p.first); putchar(' '); puts(p.second); }
template<class T, size_t size> void puts(const T (&a)[size]){ puts(a[0]); for(auto i = a; ++i != end(a); ){ putchar(' '); puts(*i); } }
template<class T> void puts(const T& a){ cout << a; }
int print(){ putchar('\n'); return 0; }
template<class T> int print(const T& t){ puts(t); putchar('\n'); return 0; }
template<class Head, class... Tail> int print(const Head& head, const Tail&... tail){ puts(head); putchar(' '); print(tail...); return 0; }
#pragma endregion

#pragma region commonly used
int digitsum(string s){
    int res=0;
    rep(i,(int)s.size()){
        res+=s[i]-'0';
    }
    return res;
}
#pragma endregion


//nCk高速
const int mod=1000000007;
const int MAX_N = 1000000;
int fact[MAX_N + 1], inv_fact[MAX_N + 1];
int mod_pow(int x, int n) {
    int res = 1;
    while (n > 0) {
        if (n & 1) res = (res * x) % mod;
        x = (x * x) % mod;
        n >>= 1;
    }
    return res;
}
int mod_inv(int x) {
    return mod_pow(x, mod - 2);
}
void nck_init() {
    fact[0] = inv_fact[0] = 1;
    for (int i = 1; i <= MAX_N; i++) {
        fact[i] = (fact[i - 1] * i) % mod;
        inv_fact[i] = mod_inv(fact[i]);
    }
}
//nCk 使う時にnck_init() を必ず入れる。
int nCk(int n, int k) {
    if (n < k) return 0;
    if (n < 0 || k < 0) return 0;
    int res = fact[n];
    res = (res * inv_fact[k]) % mod;
    res = (res * inv_fact[n - k]) % mod;
    return res;
}


vector<int> prime_fac_vec(int n) {
    vector<int> res;
    for (int i = 2; i * i <= n; i++) {
        while (n % i == 0) {
            res.push_back(i);
            n /= i;
        }
    }
    if (n != 1) res.push_back(n);
    return res;
}

map<int,int> prime_fac_map(int n) {
    map<int,int> res;
    for (int i = 2; i * i <= n; i++) {
        while (n % i == 0) {
            res[i]++;
            n /= i;
        }
    }
    if (n != 1) res[n]++;
    return res;
}

signed main(){
    INT(n,m);
    if(n<m){
        cout<<0<<endl;
        return 0;
    }
    nck_init();
    mint2 ans=0;
    int minus=1;
    rep(i,m+1){
        ans+=minus*nCk(m,i)*mod_pow(m-i,n);minus*=-1;
    }
    print(ans.val());
}