斐波那契数列(地址传递)

#include <bits/stdc++.h>
using namespace std;

int NUM ( int &a)
{
    int b=a-1;
    int c=a-2;
    if(a<=2) return 1;
    else return NUM(b) + NUM (c);
}
int main()
{
    int NUMx , NUMy;
    cin >> NUMx ;
    cout << NUM (NUMx);
    return 0;
}