/in/foo.c: In function 'validate':
/in/foo.c:17:5: warning: suggest parentheses around assignment used as truth value [-Wparentheses]
     if(k=1)//有且仅有两个数字为相同
     ^~
/in/foo.c: At top level:
/in/foo.c:31:6: warning: return type of 'main' is not 'int' [-Wmain]
 void main()
      ^~~~