#include<bits/stdc++.h>
#define int long long
#define rep(i,a,b) for(int i=(a);i<=(b);i++)
#define per(i,a,b) for(int i=(a);i>=(b);i--)
#define fi first
#define se second
#define eb emplace_back
#define popc __builtin_popcount
using namespace std;
typedef long long ll;
typedef pair<int,int> pii;
typedef vector<int> vi;
typedef vector<pii> vp;
typedef unsigned long long ull;
typedef long double ld;

int read() {
  int x=0,w=1; char c=getchar(); 
  while(!isdigit(c)) {if(c=='-') w=-1; c=getchar();}
  while(isdigit(c)) {x=x*10+(c-'0'); c=getchar();}
  return x*w;
}

const int N=3e5+9,mod=1e9+7;
int n,m,fac[N],ifac[N],inv[N],ans;

int ksm(int x,int y,int res=1) {
    for(;y;y>>=1,x=x*x%mod) if(y%2==1) res=res*x%mod;
    return res;
}
void pre(int n) {
    inv[0]=inv[1]=fac[0]=ifac[0]=1;
    rep(i,1,n) fac[i]=fac[i-1]*i%mod;
    ifac[n]=ksm(fac[n],mod-2);
    per(i,n-1,1) ifac[i]=ifac[i+1]*(i+1)%mod;
    rep(i,2,n) inv[i]=ifac[i]*fac[i-1]%mod;
}
int C(int x,int y) {
    if(x<0||y<0||x<y) return 0;
    else return fac[x]*ifac[y]%mod*ifac[x-y]%mod;
}

signed main() {
  n=read(), m=read()-1;
  pre(300000);
  rep(i,0,n) {
    int w=ksm(i,n)*C(n+1,m+i+1)%mod;
    if((n+m+i)&1) ans=(ans+mod-w)%mod;
    else ans=(ans+w)%mod;
  }
  printf("%lld\n",ans);
  return 0;
}