请指教，谢谢

#include <stdio.h>

main()

{  int s;

while ((s=getchar())!=‘＼n’)

{  switch (s-‘2’)

{     case 0:

case 1: putchar (s+4);

case 2: putchar (s+4);    break;

case 3: putchar (s+3);

default: putchar (s+2);   break;

}

printf (“＼t”);

}

}
如果输入2473，结果是多少，为什么，请指教！