/in/foo.cc: In function 'long long int exps::check(long long int, std::__cxx11::string)':
/in/foo.cc:133:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (i=1;i<st.length();)
            ~^~~~~~~~~~~~
/in/foo.cc:157:13: warning: array subscript has type 'char' [-Wchar-subscripts]
    if (mp[op][st[i]]=='>')
             ^
/in/foo.cc:167:18: warning: array subscript has type 'char' [-Wchar-subscripts]
    else if (mp[op][st[i]]=='<')
                  ^
/in/foo.cc:172:18: warning: array subscript has type 'char' [-Wchar-subscripts]
    else if (mp[op][st[i]]=='=')
                  ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:189:12: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
  for (i=0;i<s.size();i++) if (s[i]!=' ') st.push_back(s[i]);
           ~^~~~~~~~~
/in/foo.cc:198:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
   for (j=0;j<t.size();j++) if (t[j]!=' ') st.push_back(t[j]);
            ~^~~~~~~~~
/in/foo.cc: In function 'long long int exps::calc(long long int, long long int, char, long long int)':
/in/foo.cc:34:2: warning: control reaches end of non-void function [-Wreturn-type]
  }
  ^