/in/foo.c: In function 'main':
/in/foo.c:7:2: warning: implicit declaration of function 'sanf'; did you mean 'scanf'? [-Wimplicit-function-declaration]
  sanf("%d", &m);
  ^~~~
  scanf
/tmp/ccHEanl5.o: In function `main':
foo.c:(.text.startup+0x13): undefined reference to `sanf'
collect2: error: ld returned 1 exit status