C语言中静态存储类型问题

Question

include <stdio.h>
int func(int x)
{int y=0;
static int z=3;
x=z++, y++;
return(x);
}
void main()
{int a=2,i,b;
for(i=0;i<2;i++)
b=func(a++);
printf("%d\n",b);
}