/in/foo.c: In function 'DEL':
/in/foo.c:5:7: warning: array subscript has type 'char' [-Wchar-subscripts]
   if(t[a[i]]!=1){
       ^
/in/foo.c:3:10: warning: unused variable 'j' [-Wunused-variable]
  int i=0,j=0;
          ^
/in/foo.c: In function 'main':
/in/foo.c:14:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(a);
  ^~~~
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:15:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(b);
  ^~~~
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:16:9: warning: array subscript has type 'char' [-Wchar-subscripts]
  while(b[i]!='\0'){
         ^
/in/foo.c:17:6: warning: array subscript has type 'char' [-Wchar-subscripts]
   t[b[i]]=1;
      ^
/in/foo.c:17:4: warning: array subscript has type 'char' [-Wchar-subscripts]
   t[b[i]]=1;
    ^
/in/foo.c:13:45: warning: unused variable 'j' [-Wunused-variable]
  char a[100000]={0},b[10]={0},t[1000]={0},i,j;
                                             ^
/in/foo.c:16:9: warning: 'i' is used uninitialized in this function [-Wuninitialized]
  while(b[i]!='\0'){
        ~^~~
/tmp/ccEWcedg.o: In function `main':
foo.c:(.text.startup+0x46): warning: the `gets' function is dangerous and should not be used.