#include<stdio.h>
long fun(int n)
{
switch (n)
{case 0: return 0;
case 1:
case 2: return 1;
}
return fun(x-3)+fun(x-1);
}
void main()
{
    printf("%d",fun(5));
}
哪里有错啊 请高手帮我找出并改正