#include <bits/stdc++.h>
using namespace std;
int arr[1000000];
int fib(int n){
	if(arr[n]==-1){
		if(n<=1)
			arr[n] = n;
		else
			arr[n] = fib(n-1) + fib(n-2);
	}
	return arr[n];
}
int main(int argc, char const *argv[])
{
	int n;
	cout<<"Enter n: ";
	cin>>n;
	for (int i = 0; i < n+1; ++i)
	{
		arr[i] = -1;
	}
	cout<<"Fibonacci number is "<<fib(n)<<endl;
	return 0;
}