communication.cpp: In function 'void encode(int, int)':
communication.cpp:10:7: error: 'send' was not declared in this scope
10 | y=send(1);
| ^~~~
communication.cpp:14:3: error: 'send' was not declared in this scope
14 | send(0);
| ^~~~
communication.cpp: In function 'std::pair<int, int> decode(int)':
communication.cpp:23:6: error: 'receive' was not declared in this scope
23 | f=receive();
| ^~~~~~~
communication.cpp:30:1: warning: control reaches end of non-void function [-Wreturn-type]
30 | }
| ^