/in/foo.c: In function 'main':
/in/foo.c:6:2: warning: implicit declaration of function 'gets' [-Wimplicit-function-declaration]
  gets(a);
  ^~~~
/in/foo.c:19:2: warning: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
  puts(b);
  ^~~~
/tmp/ccQ7lRh4.o: In function `main':
foo.c:(.text.startup+0x11): warning: the `gets' function is dangerous and should not be used.