求大佬教，为什么xy的值输出不了------新手菜鸟

#include<stdio.h>
int main()
{
 long a,b;
 float x,y;
 printf("输入a，b:\n");
 scanf("%ld,%ld",&a,&b);
 printf("输入x，y:\n");
 scanf("%5.2f,%5.2f",&x,&y);
 printf("a=%ld\n b=%ld\n x=%5.2f\n y=%5.2f\n",a,b,x,y); 
}