answer.code: In destructor ‘IO::~IO()’:
answer.code:21:39: error: ‘stdout’ was not declared in this scope
   21 |     ~IO() {fwrite(pbuf, 1, pp - pbuf, stdout);}
      |                                       ^~~~~~
answer.code:5:1: note: ‘stdout’ is defined in header ‘<cstdio>’; did you forget to ‘#include <cstdio>’?
    4 | #include <algorithm>
  +++ |+#include <cstdio>
    5 | 
answer.code:21:12: error: ‘fwrite’ was not declared in this scope; did you mean ‘Write’?
   21 |     ~IO() {fwrite(pbuf, 1, pp - pbuf, stdout);}
      |            ^~~~~~
      |            Write
answer.code: In member function ‘void IO::Read(T&)’:
answer.code:23:73: error: ‘stdin’ was not declared in this scope
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                                         ^~~~~
answer.code:32:34: note: in expansion of macro ‘gc’
   32 |         bool sign = 0; char ch = gc(); x = 0;
      |                                  ^~
answer.code:23:73: note: ‘stdin’ is defined in header ‘<cstdio>’; did you forget to ‘#include <cstdio>’?
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                                         ^~~~~
answer.code:32:34: note: in expansion of macro ‘gc’
   32 |         bool sign = 0; char ch = gc(); x = 0;
      |                                  ^~
answer.code:23:50: error: there are no arguments to ‘fread’ that depend on a template parameter, so a declaration of ‘fread’ must be available [-fpermissive]
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                  ^~~~~
answer.code:32:34: note: in expansion of macro ‘gc’
   32 |         bool sign = 0; char ch = gc(); x = 0;
      |                                  ^~
answer.code:23:50: note: (if you use ‘-fpermissive’, G++ will accept your code, but allowing the use of an undeclared name is deprecated)
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                  ^~~~~
answer.code:32:34: note: in expansion of macro ‘gc’
   32 |         bool sign = 0; char ch = gc(); x = 0;
      |                                  ^~
answer.code:23:50: error: there are no arguments to ‘fread’ that depend on a template parameter, so a declaration of ‘fread’ must be available [-fpermissive]
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                  ^~~~~
answer.code:33:35: note: in expansion of macro ‘gc’
   33 |         for (; !isdigit(ch); ch = gc())
      |                                   ^~
answer.code:23:50: error: there are no arguments to ‘fread’ that depend on a template parameter, so a declaration of ‘fread’ must be available [-fpermissive]
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                  ^~~~~
answer.code:35:34: note: in expansion of macro ‘gc’
   35 |         for (; isdigit(ch); ch = gc()) x = x * 10 + (ch ^ 48);
      |                                  ^~
answer.code: In member function ‘void IO::Read(char*)’:
answer.code:23:73: error: ‘stdin’ was not declared in this scope
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                                         ^~~~~
answer.code:44:19: note: in expansion of macro ‘gc’
   44 |         char ch = gc();
      |                   ^~
answer.code:23:73: note: ‘stdin’ is defined in header ‘<cstdio>’; did you forget to ‘#include <cstdio>’?
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                                         ^~~~~
answer.code:44:19: note: in expansion of macro ‘gc’
   44 |         char ch = gc();
      |                   ^~
answer.code:23:50: error: ‘fread’ was not declared in this scope
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                  ^~~~~
answer.code:44:19: note: in expansion of macro ‘gc’
   44 |         char ch = gc();
      |                   ^~
answer.code: In member function ‘void IO::Read(char&)’:
answer.code:23:73: error: ‘stdin’ was not declared in this scope
   23 |     #define gc() (p1 == p2 && (p2 = (p1 = buf) + fread(buf, 1, MAXSIZE, stdin), p1 == p2) ? ' ' : *p1++)
      |                                                                         ^~~~~
answer.code:50:34: note: in expansion of macro ‘...