[Error] F:\cfree\C-Free 5\mingw\bin\指针1.c:26: error: invalid type argument of `unary *' 什么错误

#include<stdio.h>
int i,j; /*没必要声明成全局变量吧？*/
void main()
{
void inv(int *p,int m,int n);
int x,y;
printf("输入X,Y为：\n");
scanf("%d%d",&x,&y);
int a[x][y]; /*你用c89还是c99？c8