/in/foo.c: In function 'main':
/in/foo.c:11:10: warning: implicit declaration of function 'sqrt' [-Wimplicit-function-declaration]
   answer=sqrt(min*max);
          ^~~~
/in/foo.c:11:10: warning: incompatible implicit declaration of built-in function 'sqrt'
/in/foo.c:11:10: note: include '<math.h>' or provide a declaration of 'sqrt'
/in/foo.c:9:10: warning: 'answer' is used uninitialized in this function [-Wuninitialized]
  while (((int)answer+1)!=x)
          ^~~~~~~~~~~