#include<bits/stdc++.h>
#define ALL(v) std::begin(v),std::end(v)
using lint=long long;
using ld=long double;
template<class T>using numr=std::numeric_limits<T>;
lint mod=1'000'000'007;/*{{{*/
lint inverse(lint x){
    assert(x%mod);
    lint y=1,u=mod,v=0;
    while(x){lint q=u/x;u-=q*x;std::swap(u,x);v-=q*y;std::swap(v,y);}
    assert(x==0&&std::abs(u)==1&&std::abs(y)==mod&&std::abs(v)<mod);
    return v<0?v+mod:v;
}
lint normalized(lint x){if(x<=-mod||mod<=x)x%=mod;if(x<0)x+=mod;return x;}
struct mint{
    lint value;
    mint()=default;
    mint(lint x):value(normalized(x)){}
};
std::ostream&operator<<(std::ostream&os,mint x){return os<<x.value;}
mint operator+(mint x,mint y){lint z=x.value+y.value;if(mod<=z)z-=mod;return mint{z};}
mint operator-(mint x,mint y){lint z=x.value-y.value;if(z<0)z+=mod;return mint{z};}
mint operator*(mint x,mint y){return mint{x.value*y.value%mod};}
mint operator/(mint x,mint y){return mint{x.value*inverse(y.value)%mod};}
mint&operator+=(mint&x,mint y){return x=x+y;}
mint&operator-=(mint&x,mint y){return x=x-y;}
mint&operator*=(mint&x,mint y){return x=x*y;}
mint&operator/=(mint&x,mint y){return x=x/y;}
bool operator==(mint x,mint y){return x.value==y.value;}
bool operator!=(mint x,mint y){return x.value!=y.value;}
mint power(mint x,lint y){mint z=1;for(;y;y>>=1){if(y&1)z*=x;x*=x;}return z;}/*}}}*/
struct factorials{
    lint sz;std::vector<mint>fact,finv;
    factorials(lint n):sz(n),fact(n),finv(n){
        fact.at(0)=1;
        for(lint i=1;i<n;i++)fact.at(i)=fact.at(i-1)*i;
        finv.at(n-1)=mint{1}/fact.at(n-1);
        for(lint i=n-1;i>=1;i--)finv.at(i-1)=finv.at(i)*i;
    }
    mint operator()(lint x)const{return fact.at(x);}
    mint inv(lint x)const{return finv.at(x);}
    mint binom(lint n,lint k){assert(0<=n&&n<sz);return k<0||n<k?0:fact.at(n)*finv.at(k)*finv.at(n-k);}
};
int main(){
    std::cin.tie(nullptr);std::ios_base::sync_with_stdio(false);
    std::cout.setf(std::ios_base::fixed);std::cout.precision(15);
    lint n,m;std::cin>>n>>m;
    factorials fact(m+1);
    mint ans=0;
    for(lint i=1;i<=m;i++){
        mint now=((m-i)%2?-1:1)*fact.binom(m,i)*power(mint{i},n);
        ans+=now;
    }
    std::cout<<ans<<'\n';
}