/in/foo.c: In function 'main':
/in/foo.c:5:2: warning: implicit declaration of function 'scanf_s' [-Wimplicit-function-declaration]
  scanf_s("%d,%d", &x1, &x2);
  ^~~~~~~
/in/foo.c:6:2: warning: implicit declaration of function 'printf_s' [-Wimplicit-function-declaration]
  printf_s("%d\n", x1 + x2);
  ^~~~~~~~
/in/foo.c:4:20: warning: unused variable 'y3' [-Wunused-variable]
  int x1, x2 ,y1,y2,y3;
                    ^~
/in/foo.c:4:17: warning: unused variable 'y2' [-Wunused-variable]
  int x1, x2 ,y1,y2,y3;
                 ^~
/in/foo.c:4:14: warning: unused variable 'y1' [-Wunused-variable]
  int x1, x2 ,y1,y2,y3;
              ^~
/tmp/cctTttkE.o: In function `main':
foo.c:(.text.startup+0x18): undefined reference to `scanf_s'
foo.c:(.text.startup+0x2e): undefined reference to `printf_s'
foo.c:(.text.startup+0x45): undefined reference to `printf_s'
foo.c:(.text.startup+0x5e): undefined reference to `printf_s'
collect2: error: ld returned 1 exit status