Number of ways to reach nth stair using recursion.

#include <iostream>
#include <vector>
using namespace std;
 
int Fibonacci(int n, vector<int>& memoVector)
{
  if(n == 0 || n == 1)
    return 1;
    
  if(memoVector[n] != -1)
    return memoVector[n];
    
  return memoVector[n] = Fibonacci(n-1, memoVector) + Fibonacci(n-2, memoVector);
}
 
int main() 
{
  int n;
  cin >> n;
  vector<int> memoVector(n+1, -1);
  
  cout << "Ways to reach " << n << "th stair: " << Fibonacci(n, memoVector) << endl;
  
  return 0;
}