foo.c: In function 'main':
foo.c:7:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
    7 |  gets(s);
      |  ^~~~
In file included from /usr/include/stdio.h:867,
                 from foo.c:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:235:1: note: declared here
  235 | gets (char *__str)
      | ^~~~
foo.c:6:6: warning: unused variable 'i' [-Wunused-variable]
    6 |  int i,si,len;
      |      ^
foo.c: In function 'del':
foo.c:15:10: warning: unused variable 'k' [-Wunused-variable]
   15 |  int i,j,k;
      |          ^
foo.c: In function 'main':
foo.c:7:2: warning: ignoring return value of 'gets', declared with attribute warn_unused_result [-Wunused-result]
    7 |  gets(s);
      |  ^~~~~~~
foo.c:8:2: warning: ignoring return value of 'scanf', declared with attribute warn_unused_result [-Wunused-result]
    8 |  scanf("%d %d",&si,&len);
      |  ^~~~~~~~~~~~~~~~~~~~~~~
/usr/bin/ld: /tmp/ccPYR2Ry.o: in function `main':
foo.c:(.text.startup+0x46): warning: the `gets' function is dangerous and should not be used.

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