Language: C++

//JOI??¬?????????????????????

#include<iostream>
#include<algorithm>
using namespace std;

long long JOI??¬??????????????????(long long a, long long b, long long &x, long long &y) {
	long long d;
	if (b == 0) {
		d = a;
		x = 1; y = 0;
	}
	else {
		d = JOI??¬??????????????????(b, a%b, y, x);
		y -= a / b*x;
	}
	return d;
}

int main() {
	long long a, b, x, y;
	cin >> a >> b;
	JOI??¬??????????????????(a, b, x, y);
	cout << x << ' ' << y << endl;
	return 0;
}

Compiler output:
a.cc:7:16: error: extended character ¬ is not valid in an identifier
    7 | long long JOI??¬??????????????????(long long a, long long b, long long &x, long long &y) {
      |                ^
a.cc:7:33: warning: trigraph ??( ignored, use -trigraphs to enable [-Wtrigraphs]
    7 | long long JOI??¬??????????????????(long long a, long long b, long long &x, long long &y) {
a.cc:14:26: error: extended character ¬ is not valid in an identifier
   14 |                 d = JOI??¬??????????????????(b, a%b, y, x);
      |                          ^
a.cc:14:43: warning: trigraph ??( ignored, use -trigraphs to enable [-Wtrigraphs]
   14 |                 d = JOI??¬??????????????????(b, a%b, y, x);
a.cc:23:14: error: extended character ¬ is not valid in an identifier
   23 |         JOI??¬??????????????????(a, b, x, y);
      |              ^
a.cc:23:31: warning: trigraph ??( ignored, use -trigraphs to enable [-Wtrigraphs]
   23 |         JOI??¬??????????????????(a, b, x, y);
a.cc:7:14: error: expected initializer before '?' token
    7 | long long JOI??¬??????????????????(long long a, long long b, long long &x, long long &y) {
      |              ^
a.cc: In function 'int main()':
a.cc:23:9: error: 'JOI' was not declared in this scope
   23 |         JOI??¬??????????????????(a, b, x, y);
      |         ^~~
a.cc:23:13: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |             ^
a.cc:23:14: error: '\U000000ac' was not declared in this scope
   23 |         JOI??¬??????????????????(a, b, x, y);
      |              ^
a.cc:23:16: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                ^
a.cc:23:17: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                 ^
a.cc:23:18: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                  ^
a.cc:23:19: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                   ^
a.cc:23:20: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                    ^
a.cc:23:21: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                     ^
a.cc:23:22: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                      ^
a.cc:23:23: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                       ^
a.cc:23:24: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                        ^
a.cc:23:25: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                         ^
a.cc:23:26: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                          ^
a.cc:23:27: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                           ^
a.cc:23:28: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                            ^
a.cc:23:29: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                             ^
a.cc:23:30: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                              ^
a.cc:23:31: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                               ^
a.cc:23:32: error: expected primary-expression before '?' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                ^
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token
a.cc:23:45: error: expected ':' before ';' token
   23 |         JOI??¬??????????????????(a, b, x, y);
      |                                             ^
      |                                             :
a.cc:23:45: error: expected primary-expression before ';' token