C语言求按顺序排列随机输入的三个数，下面程序出错在哪里

Question

 #include<stdio.h>   int main()   {   void exchange(int x,int y);   int a,b,c;   printf("please input three numbers:\n");   scanf("%d,%d,%d",&a,&b,&c);   if(a<b) exchange(a,b);  if(a<c) exchange(a,c);  if(b<c) exchange(b,c);  printf("the order is %d,%d,%d\n",a,b,c);return 0;  } void exchange(int x,int y) {int m;  m=x;  x=y;  y=m;}