C++求斐波那契数列的第n项

#include <iostream>
using namespace std;

int fib(int n);

int main()
{
    int a;
    while(cin>>a)
    {
        cout<<"the result: "<<fib(a)<<endl;
    }
    return 0;
}
int fib(int n)
{
    if(n==1||n==2)
        return 1;
    else
        return fib(n-1)+fib(n-2);

}