foo.cc: In member function 'void expr::scan()':
foo.cc:60:19: warning: comparison of integer expressions of different signedness: 'int' and 'size_t' {aka 'long unsigned int'} [-Wsign-compare]
   60 | for (i=0,j=0,k=0;i<strlen(ts);i++)
      |                  ~^~~~~~~~~~~
foo.cc: In function 'int main()':
foo.cc:109:6: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
  109 | fgets(ss,sizeof(ss),stdin);
      | ~~~~~^~~~~~~~~~~~~~~~~~~~~
foo.cc: In member function 'void expr::scan()':
foo.cc:59:6: warning: ignoring return value of 'char* fgets(char*, int, FILE*)', declared with attribute warn_unused_result [-Wunused-result]
   59 | fgets(ts,sizeof(ts),stdin);
      | ~~~~~^~~~~~~~~~~~~~~~~~~~~
In file included from /usr/include/string.h:495,
                 from /usr/include/c++/9/cstring:42,
                 from /usr/include/x86_64-linux-gnu/c++/9/bits/stdc++.h:48,
                 from foo.cc:1:
In function 'char* strcat(char*, const char*)',
    inlined from 'void expr::scan()' at foo.cc:76:7:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:128:33: warning: 'char* __builtin_strcat(char*, const char*)' accessing 101 or more bytes at offsets 100 and 0 may overlap 1 byte at offset 100 [-Wrestrict]
  128 |   return __builtin___strcat_chk (__dest, __src, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~
In function 'char* strcat(char*, const char*)',
    inlined from 'void expr::scan()' at foo.cc:76:7,
    inlined from 'int main()' at foo.cc:113:7:
/usr/include/x86_64-linux-gnu/bits/string_fortified.h:128:33: warning: 'char* __builtin___strcat_chk(char*, const char*, long unsigned int)' accessing 101 or more bytes at offsets 100 and 0 may overlap 1 byte at offset 100 [-Wrestrict]
  128 |   return __builtin___strcat_chk (__dest, __src, __bos (__dest));
      |          ~~~~~~~~~~~~~~~~~~~~~~~^~~~~~~~~~~~~~~~~~~~~~~~~~~~~~~

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