/in/foo.c: In function 'main':
/in/foo.c:11:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(str1);
  ^~~~
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:12:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(str2);
  ^~~~
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:13:2: warning: 'gets' is deprecated [-Wdeprecated-declarations]
  gets(str3);
  ^~~~
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:28:4: warning: this 'for' clause does not guard... [-Wmisleading-indentation]
    for(j=0;j<len2;j++)
    ^~~
/in/foo.c:35:5: note: ...this statement, but the latter is misleadingly indented as if it were guarded by the 'for'
     if(flag==1)
     ^~
/in/foo.c:15:6: warning: variable 'len1' set but not used [-Wunused-but-set-variable]
  int len1,len2,len3;
      ^~~~
/tmp/ccFzCxjb.o: In function `main':
foo.c:(.text.startup+0x2a): warning: the `gets' function is dangerous and should not be used.