Răspuns:
#include <iostream>
#include <cmath>
#include <algorithm>
using namespace std;
int a,b;
long long prod=1;
int main()
{
cin>>a>>b;
int vmin=min(a,b);
int vmax=max(a,b);
vmin++,vmax--;
if(vmin%2==1)
vmin++;
for(int i=vmin;i<=vmax;i+=2)
prod*=i;
cout<<prod;
return 0;
}