/in/foo.c: In function 'main':
/in/foo.c:4:2: warning: implicit declaration of function 'gets' [-Wimplicit-function-declaration]
  gets(s);
  ^~~~
/in/foo.c:13:2: warning: implicit declaration of function 'puts' [-Wimplicit-function-declaration]
  puts(s);
  ^~~~
/tmp/ccG5aAod.o: In function `main':
foo.c:(.text.startup+0x11): warning: the `gets' function is dangerous and should not be used.