Main.cc: In function ‘int main()’:
Main.cc:10:10: error: ‘A’ was not declared in this scope
cin>>A>>B>>C;
^
Main.cc:10:13: error: ‘B’ was not declared in this scope
cin>>A>>B>>C;
^
Main.cc:10:16: error: ‘C’ was not declared in this scope
cin>>A>>B>>C;
^