/in/foo.c: In function 'main':
/in/foo.c:4:1: warning: implicit declaration of function 'scans' [-Wimplicit-function-declaration]
 scans("%s",s);
 ^~~~~
/tmp/ccGFyu87.o: In function `main':
foo.c:(.text.startup+0x17): undefined reference to `scans'
collect2: error: ld returned 1 exit status