/in/foo.cc: In function 'double solve(char*, double)':
/in/foo.cc:49:13: warning: comparison between signed and unsigned integer expressions [-Wsign-compare]
    while (j < strlen(str) && str[j] >= '0' && str[j] <= '9')
           ~~^~~~~~~~~~~~~
/in/foo.cc:79:38: warning: array subscript has type 'char' [-Wchar-subscripts]
   while (!ope.empty() && level[str[i]] <= level[ope.top()])
                                      ^
/in/foo.cc:79:58: warning: array subscript has type 'char' [-Wchar-subscripts]
   while (!ope.empty() && level[str[i]] <= level[ope.top()])
                                                          ^
/in/foo.cc: In function 'int main()':
/in/foo.cc:110:2: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(st);
  ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:110:9: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
  gets(st);
         ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:115:3: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   gets(s[i]);
   ^~~~
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc:115:12: warning: 'char* gets(char*)' is deprecated [-Wdeprecated-declarations]
   gets(s[i]);
            ^
In file included from /usr/include/c++/6/cstdio:42:0,
                 from /in/foo.cc:1:
/usr/include/stdio.h:640:14: note: declared here
 extern char *gets (char *__s) __wur __attribute_deprecated__;
              ^~~~
/in/foo.cc: In function 'double cal(double, double, char)':
/in/foo.cc:31:1: warning: control reaches end of non-void function [-Wreturn-type]
 }
 ^
/tmp/ccDCw8Yw.o: In function `main':
foo.cc:(.text.startup+0x44): warning: the `gets' function is dangerous and should not be used.