answer.code:3:1: error: stray ‘\’ in program
    3 | \#include<algorithm>
      | ^
answer.code:3:2: error: stray ‘#’ in program
    3 | \#include<algorithm>
      |  ^
answer.code:3:3: error: ‘include’ does not name a type
    3 | \#include<algorithm>
      |   ^~~~~~~
In file included from answer.code:5:
/usr/include/c++/11/cmath:83:11: error: ‘acos’ has not been declared in ‘::’
   83 |   using ::acos;
      |           ^~~~
/usr/include/c++/11/cmath:102:11: error: ‘asin’ has not been declared in ‘::’
  102 |   using ::asin;
      |           ^~~~
/usr/include/c++/11/cmath:121:11: error: ‘atan’ has not been declared in ‘::’
  121 |   using ::atan;
      |           ^~~~
/usr/include/c++/11/cmath:140:11: error: ‘atan2’ has not been declared in ‘::’
  140 |   using ::atan2;
      |           ^~~~~
/usr/include/c++/11/cmath:161:11: error: ‘ceil’ has not been declared in ‘::’
  161 |   using ::ceil;
      |           ^~~~
/usr/include/c++/11/cmath:180:11: error: ‘cos’ has not been declared in ‘::’
  180 |   using ::cos;
      |           ^~~
/usr/include/c++/11/cmath:199:11: error: ‘cosh’ has not been declared in ‘::’
  199 |   using ::cosh;
      |           ^~~~
/usr/include/c++/11/cmath:218:11: error: ‘exp’ has not been declared in ‘::’
  218 |   using ::exp;
      |           ^~~
/usr/include/c++/11/cmath:237:11: error: ‘fabs’ has not been declared in ‘::’
  237 |   using ::fabs;
      |           ^~~~
/usr/include/c++/11/cmath:256:11: error: ‘floor’ has not been declared in ‘::’
  256 |   using ::floor;
      |           ^~~~~
/usr/include/c++/11/cmath:275:11: error: ‘fmod’ has not been declared in ‘::’
  275 |   using ::fmod;
      |           ^~~~
/usr/include/c++/11/cmath:296:11: error: ‘frexp’ has not been declared in ‘::’
  296 |   using ::frexp;
      |           ^~~~~
/usr/include/c++/11/cmath:315:11: error: ‘ldexp’ has not been declared in ‘::’
  315 |   using ::ldexp;
      |           ^~~~~
/usr/include/c++/11/cmath:334:11: error: ‘log’ has not been declared in ‘::’
  334 |   using ::log;
      |           ^~~
/usr/include/c++/11/cmath:353:11: error: ‘log10’ has not been declared in ‘::’
  353 |   using ::log10;
      |           ^~~~~
/usr/include/c++/11/cmath:372:11: error: ‘modf’ has not been declared in ‘::’
  372 |   using ::modf;
      |           ^~~~
/usr/include/c++/11/cmath:384:11: error: ‘pow’ has not been declared in ‘::’
  384 |   using ::pow;
      |           ^~~
/usr/include/c++/11/cmath:421:11: error: ‘sin’ has not been declared in ‘::’
  421 |   using ::sin;
      |           ^~~
/usr/include/c++/11/cmath:440:11: error: ‘sinh’ has not been declared in ‘::’
  440 |   using ::sinh;
      |           ^~~~
/usr/include/c++/11/cmath:459:11: error: ‘sqrt’ has not been declared in ‘::’
  459 |   using ::sqrt;
      |           ^~~~
/usr/include/c++/11/cmath:478:11: error: ‘tan’ has not been declared in ‘::’
  478 |   using ::tan;
      |           ^~~
/usr/include/c++/11/cmath:497:11: error: ‘tanh’ has not been declared in ‘::’
  497 |   using ::tanh;
      |           ^~~~
/usr/include/c++/11/cmath:1065:11: error: ‘double_t’ has not been declared in ‘::’
 1065 |   using ::double_t;
      |           ^~~~~~~~
/usr/include/c++/11/cmath:1066:11: error: ‘float_t’ has not been declared in ‘::’
 1066 |   using ::float_t;
      |           ^~~~~~~
/usr/include/c++/11/cmath:1069:11: error: ‘acosh’ has not been declared in ‘::’
 1069 |   using ::acosh;
      |           ^~~~~
/usr/include/c++/11/cmath:1070:11: error: ‘acoshf’ has not been declared in ‘::’
 1070 |   using ::acoshf;
      |           ^~~~~~
/usr/include/c++/11/cmath:1071:11: error: ‘acoshl’ has not been declared in ‘::’
 1071 |   using ::acoshl;
      |           ^~~~~~
/usr/include/c++/11/cmath:1073:11: error: ‘asinh’ has not been declared in ‘::’
 1073 |   using ::asinh;
      |           ^~~~~
/usr/include/c++/11/cmath:1074:11: error: ‘asinhf’ has not been declared in ‘::’
 1074 |   using ::asinhf;
      |           ^~~~~~
/usr/include/c++/11/cmath:1075:11: error: ‘asinhl’ has not been declared in ‘::’
 1075 |   using ::asinhl;
      |           ^~~~~~
/usr/include/c++/11/cmath:1077:11: error: ‘atanh’ has not been declared in ‘::’
 1077 |   using ::atanh;
      |           ^~~~~
/usr/include/c++/11/cmath:1078:11: error: ‘atanhf’ has not been declared in ‘::’
 1078 |   using ::atanhf;
      |           ^~~~~~
/usr/include/c++/11/cmath:1079:11: error: ‘atanhl’ has not been declared in ‘::’
 1079 |   using ::atanhl;
      |           ^~~~~~
/usr/include/c++/11/cmath:1081:11: error: ‘cbrt’ has not been declared in ‘::’
 1081 |   using ::cbrt;
      |           ^~~~
/usr/include/c++/11/cmath:1082:11: error: ‘cbrtf’ has not been declared in ‘::’
 1082 |   using ::cbrtf;
      |           ^~~~~
/usr/include/c++/11/cmath:1083:11: error: ‘cbrtl’ has not been declared in ‘::’
 1083 |   using ::cbrtl;
      |           ^~~~~
/usr/include/c++/11/cmath:1085:11: error: ‘copysign’ has not been declared in ‘::’
 1085 |   using ::copysign;...