C语言代码的修改问题

#define x 3.5
#define a 5.5
{
    float x,y;
    y=x+z;
    printf("a=%f,x=%f,y=%f\n",a,x,y);
}

#include <stdio.h>
#define x 3.5
#define a 5.5
int main(){
    float z = 0,y = 0;
    y=x+z;
    printf("a=%f,x=%f,y=%f\n",a,x,y);
    return 0;
}

｛前加上函数名int main()
顶部再加个头文件 #indclude <stdio.h>