/in/foo.cc: In function 'int main()':
/in/foo.cc:10:14: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   10 |  while(gets(a)!=NULL)
      |              ^
In file included from /usr/include/stdio.h:867,
                 from /usr/include/c++/9/cstdio:42,
                 from /usr/include/c++/9/ext/string_conversions.h:43,
                 from /usr/include/c++/9/bits/basic_string.h:6496,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from /in/foo.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:235:1: note: declared here
  235 | gets (char *__str)
      | ^~~~
/in/foo.cc:10:14: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   10 |  while(gets(a)!=NULL)
      |              ^
In file included from /usr/include/stdio.h:867,
                 from /usr/include/c++/9/cstdio:42,
                 from /usr/include/c++/9/ext/string_conversions.h:43,
                 from /usr/include/c++/9/bits/basic_string.h:6496,
                 from /usr/include/c++/9/string:55,
                 from /usr/include/c++/9/bits/locale_classes.h:40,
                 from /usr/include/c++/9/bits/ios_base.h:41,
                 from /usr/include/c++/9/ios:42,
                 from /usr/include/c++/9/ostream:38,
                 from /usr/include/c++/9/iostream:39,
                 from /in/foo.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:235:1: note: declared here
  235 | gets (char *__str)
      | ^~~~
/in/foo.cc:12:3: error: 'm' was not declared in this scope
   12 |   m=strlen(a)
      |   ^
/in/foo.cc:12:5: error: 'strlen' was not declared in this scope
   12 |   m=strlen(a)
      |     ^~~~~~
/in/foo.cc:2:1: note: 'strlen' is defined in header '<cstring>'; did you forget to '#include <cstring>'?
    1 | #include <iostream>
  +++ |+#include <cstring>
    2 | #include<stdio.h>
/in/foo.cc:13:18: error: 'i' was not declared in this scope
   13 |      for(int i=0;i<m;i++)
      |                  ^