number of BST possible for n nodes

#include<iostream>
using namespace std;

int TotalBSTPossible(int n){
  if(n<=1)
    return 1;
  int sum=0;
  for(int root=1;root<=n;root++){
   int left=TotalBSTPossible(root-1);
   int right=TotalBSTPossible(n-root);
   sum+=left*right;
   }
  return sum;
  }
int main(){
  int n=4;
  cout<<TotalBSTPossible(n);
  return 0;
  }