谁能帮我修改一下这个速算24的c 把自己输入4个数改为系统从13张扑克牌中抽取进行运算

#include<stdio.h>
#include <conio.h>
int enumerate(int ans);

char op[]={'+','-','*','/'};
char *model[]=
{
"((AxB)yC)zD",
"(Ay(BxC))zD",
"Az(By(CxD))",
"Az((BxC)yD)",
"(AxB)z(CyD)"
};
int *A, *B, *C, *D;
char *x, *y ,*z;
int ***opd;
char ***opr;
char *sample;
int **oprand[]={&A,&B,&C,&D};
char **oprator[]={&x,&y,&z};
int a[4];
int main(void)
{
int i;
char l;
start:clrscr();
printf("Enter %d numbers.\n",4);
for(i=0;i<sizeof a/sizeof a[0];i++)
scanf("%d",a+i);
if(enumerate(24)==0)
printf("No solution!\n");
printf("\nContinue?y/