ppp

#include<bits/stdc++.h>
using namespace std;

long long a[10005][10005];
bool b[10005][10005];
const long long p=100000007;

void f(int x,int y){
if(x==1 || y==1){
a[x][y]=1;
}else if(x==y){
a[x][y]=1;
}else if(x>y){
f(x-1,y);
f(x-1,y-1);
a[x][y]=a[x-1][y]%p+a[x-1][y-1]%p;
cout<<x<<" "<<y<<" "<<a[x][y]<<endl;
}
}

int main(){
long long n,m;
cin>>n>>m;
for(int i=1; i<=n; i++){
a[i][1]=1;
}
f(n,m);
cout<<a[n][m]*2<<endl;
return 0;
}