#include<cstdio>

#include<cstdlib>

#include<iostream>

#include<fstream>

#include<algorithm>

#include<cstring>

#include<string>

#include<cmath>

#include<queue>

#include<stack>

#include<map>

#include<utility>

#include<set>

#include<bitset>

#include<vector>

#include<functional>

#include<deque>

#include<cctype>

#include<climits>

#include<complex>

//#include<bits/stdc++.h>适用于CF,UOJ，但不适用于poj

using namespace std;

typedef long long LL;

typedef double DB;

typedef pair<int,int> PII;

typedef complex<DB> CP;

#define mmst(a,v) memset(a,v,sizeof(a))

#define mmcy(a,b) memcpy(a,b,sizeof(a))

#define fill(a,l,r,v) fill(a+l,a+r+1,v)

#define re(i,a,b)  for(i=(a);i<=(b);i++)

#define red(i,a,b) for(i=(a);i>=(b);i--)

#define ire(i,x) for(typedef(x.begin()) i=x.begin();i!=x.end();i++)

#define fi first

#define se second

#define m_p(a,b) make_pair(a,b)

#define p_b(a) push_back(a)

#define SF scanf

#define PF printf

#define two(k) (1<<(k))

template<class T>inline T sqr(T x){return x*x;}

template<class T>inline void upmin(T &t,T tmp){if(t>tmp)t=tmp;}

template<class T>inline void upmax(T &t,T tmp){if(t<tmp)t=tmp;}

const DB EPS=1e-;

inline int sgn(DB x){if(abs(x)<EPS)return ;return(x>)?:-;}

const DB Pi=acos(-1.0);

inline int gint()

  {

        int res=;bool neg=;char z;

        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());

        if(z==EOF)return ;

        if(z=='-'){neg=;z=getchar();}

        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());

        return (neg)?-res:res;

    }

inline LL gll()

  {

      LL res=;bool neg=;char z;

        for(z=getchar();z!=EOF && z!='-' && !isdigit(z);z=getchar());

        if(z==EOF)return ;

        if(z=='-'){neg=;z=getchar();}

        for(;z!=EOF && isdigit(z);res=res*+z-'',z=getchar());

        return (neg)?-res:res;

    }

const LL Mod=;

LL N,M;

LL ans;

inline LL power(LL a,LL k)

  {

      LL x=;

        while(k){if(k&)x=x*a%Mod;a=a*a%Mod;k>>=;}

        return x;

    }

LL S[];

inline LL C(LL N,LL M)

  {

      if(M< || M>N)return ;

      LL x=S[N],y=S[N-M]*S[M]%Mod,res;

      res=x*power(y,Mod-)%Mod;

      res=(res%Mod+Mod)%Mod;

      return res;

  }

//y=x+1

//y=x-M-2

inline void change(LL &x,LL &y,int f)

  {

      LL dx,dy;

      if(f==)

        {

            dx=x;dy=y-;

            x=dy;y=dx;

            y++;

            }

        else

          {

              dx=x;dy=y+M+;

              x=dy;y=dx;

              y-=M+;

          }

  }

int main()

  {

      freopen("bzoj4005.in","r",stdin);

      freopen("bzoj4005.out","w",stdout);

      LL i;

      S[]=;re(i,,)S[i]=S[i-]*i%Mod;

      N=gll(),M=gll();

        ans=C(N+N+M+,N);LL x,y;int f;

      x=N+M+;y=N;f=;

      while()

        {

            change(x,y,f);

            if(!(x>= && y>=))break;

            if(f==) ans=(ans-C(x+y,x))%Mod; else ans=(ans+C(x+y,x))%Mod;

            f^=;

        }

      x=N+M+;y=N;f=;

      while()

        {

            change(x,y,f);

            if(!(x>= && y>=))break;

            if(f==) ans=(ans-C(x+y,x))%Mod; else ans=(ans+C(x+y,x))%Mod;

            f^=;

        }

      ans=(ans%Mod+Mod)%Mod;

      cout<<ans<<endl;

      return ;

  }