foo.cc: In function 'int main()':
foo.cc:16:36: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
         for (i=0;i<L;i++) gets(I[i]);   
                                    ^
In file included from /usr/include/stdio.h:862:0,
                 from /usr/include/c++/7/cstdio:42,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:46,
                 from foo.cc:1:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:232:1: note: declared here
 gets (char *__str)
 ^~~~
foo.cc:20:27: warning: array subscript has type 'char' [-Wchar-subscripts]
                 if (f[n[0]]++) break; //err: used variable
                           ^
foo.cc:20:28: warning: use of an operand of type 'bool' in 'operator++' is deprecated [-Wdeprecated]
                 if (f[n[0]]++) break; //err: used variable
                            ^~
foo.cc:31:32: warning: array subscript has type 'char' [-Wchar-subscripts]
                 f[S.top().first]=0;
                                ^
foo.cc:37:43: warning: array subscript has type 'char' [-Wchar-subscripts]
         while (!S.empty()) f[S.top().first]=0, S.pop(); 
                                           ^
foo.cc:11:10: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
     scanf("%d",&T);
     ~~~~~^~~~~~~~~
foo.cc:14:14: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result]
         scanf("%d%s\n",&L,O); //do not omit '\n'
         ~~~~~^~~~~~~~~~~~~~~
foo.cc:16:31: warning: ignoring return value of 'char* gets(char*)', declared with attribute warn_unused_result [-Wunused-result]
         for (i=0;i<L;i++) gets(I[i]);   
                           ~~~~^~~~~~
In file included from /usr/include/stdio.h:862:0,
                 from /usr/include/c++/7/cstdio:42,
                 from /usr/include/x86_64-linux-gnu/c++/7/bits/stdc++.h:46,
                 from foo.cc:1:
In function 'char* gets(char*)',
    inlined from 'int main()' at foo.cc:16:31:
/usr/include/x86_64-linux-gnu/bits/stdio2.h:236:28: warning: call to '__gets_warn' declared with attribute warning: please use fgets or getline instead, gets can't specify buffer size
   return __gets_warn (__str);
                            ^
/tmp/cc1WtnPz.o: In function `main':
foo.cc:(.text.startup+0xab): warning: the `gets' function is dangerous and should not be used.

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