/in/foo.c: In function 'main':
/in/foo.c:5:20: error: 'x' undeclared (first use in this function)
     scanf("%d %d",&x, &y);
                    ^
/in/foo.c:5:20: note: each undeclared identifier is reported only once for each function it appears in
/in/foo.c:5:24: error: 'y' undeclared (first use in this function)
     scanf("%d %d",&x, &y);
                        ^
/in/foo.c:7:9: warning: passing argument 1 of 'printf' makes pointer from integer without a cast [-Wint-conversion]
  printf(z);
         ^
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:364:12: note: expected 'const char * restrict' but argument is of type 'int'
 extern int printf (const char *__restrict __format, ...);
            ^~~~~~