/in/foo.c: In function 'main':
/in/foo.c:128:17: warning: 'z' may be used uninitialized in this function [-Wmaybe-uninitialized]
                 printf("%d\n",z);
                 ^~~~~~~~~~~~~~~~
/tmp/ccNqPjtc.o: In function `main':
foo.c:(.text.startup+0x11): undefined reference to `Get_Char'
foo.c:(.text.startup+0x33): undefined reference to `Get_Char'
foo.c:(.text.startup+0x63): undefined reference to `Get_Char'
foo.c:(.text.startup+0x8c): undefined reference to `Get_Char'
foo.c:(.text.startup+0xa3): undefined reference to `Get_Char'
/tmp/ccNqPjtc.o:foo.c:(.text.startup+0xcc): more undefined references to `Get_Char' follow
collect2: error: ld returned 1 exit status