/in/foo.cc: In function 'int main()':
/in/foo.cc:39:9: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   gets(s);
         ^
In file included from /usr/include/c++/7/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:32:14: warning: unused variable 'ch' [-Wunused-variable]
  char s[100],ch;
              ^~
/in/foo.cc: In function 'void doit(int, int)':
/in/foo.cc:12:26: warning: array subscript is above array bounds [-Warray-bounds]
  t=0;w=1;h[1][1]=p;h[1][2]=q;
                    ~~~~~~^
/in/foo.cc:19:12: warning: array subscript is above array bounds [-Warray-bounds]
    y=h[t][2]+dy[i];
      ~~~~~~^
/in/foo.cc:24:11: warning: array subscript is above array bounds [-Warray-bounds]
     h[w][2]=y;
     ~~~~~~^
/tmp/ccgJVatQ.o: In function `main':
foo.cc:(.text.startup+0xac): warning: the `gets' function is dangerous and should not be used.