/in/foo.c: In function 'main':
/in/foo.c:18:4: warning: 'gets' is deprecated [-Wdeprecated-declarations]
    gets(y[k][i]);
    ^~~~
In file included from /in/foo.c:1:0:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.c:45:6: warning: variable 'b' set but not used [-Wunused-but-set-variable]
  int b[400]={0},dq=0,a=m*n;
      ^
/in/foo.c:13:13: warning: unused variable 'j0' [-Wunused-variable]
  int i,j,i0,j0,k;
             ^~
/in/foo.c:13:10: warning: unused variable 'i0' [-Wunused-variable]
  int i,j,i0,j0,k;
          ^~
/tmp/ccW3Rrvx.o: In function `main':
foo.c:(.text.startup+0x74): warning: the `gets' function is dangerous and should not be used.