Why isnt my code getting AC

#1 
#include<iostream>
using namespace std;
#define ll long long
int main() {
	ll n;
	
	cin>>n;

	//while(n--) {
			if(n==0 || n==1){
				cout<<"1"<<endl;
				return 0;
			}
		

		ll i = n+2, j = 1; 
		double ans = 1.0;
		while(i <= (2*n) && j <= n){
			ans = (ans * i)/j;
			i++;
			j++;
		}

		while(i <= (2*n)){
			ans = ans * i;
			i++;
		}

		while(j <= n){
			ans = ans/j;
			j++;
		}

		cout<<(long long)ans<<endl;
//	}
	

	return 0;
}

I wrote a code for this problem and I have matched the output for all test cases given in the soutlion tab sitll my amswer is not getting AC, my code is giving the right output though

#2

@sudipt1999
This is a problem for big integers. Catalan Numbers grow extremely fast. Storing such large integers is not possible in C++.
You have to use either Java BigInteger class or Python to solve this problem. Can’t solve it in C++.

#3

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