#include <bits/stdc++.h> using namespace std; long long n,m,c,d; long long a(int n){ if(n<2){ return 1; } else{ return n*a(n-1); } } int main(){ cin>>n>>m; if(n%2==0 and m%2==0){ cout<<"0"; return 0; } if(n%2==0){ c=n/2-1; } else{ c=(n+1)/2-1; } if(m%2==0){ d=m/2-1; } else{ d=(m+1)/2-1; } // cout<<"c="<<c<<" "<<"d="<<d<<endl; cout<<(a(c+d)/a(d))/a(c); return 0; }