Eroare de compilare: main.cpp: In function 'int main()': main.cpp:6:23: error: invalid use of incomplete type 'std::ifstream {aka class std::basic_ifstream<char>}' ifstream("adunare.in") ^ In file included from /usr/include/c++/6/ios:38:0, from /usr/include/c++/6/ostream:38, from /usr/include/c++/6/iostream:39, from main.cpp:1: /usr/include/c++/6/iosfwd:116:11: note: declaration of 'std::ifstream {aka class std::basic_ifstream<char>}' class basic_ifstream; ^~~~~~~~~~~~~~ main.cpp:5:6: warning: unused variable 'a' [-Wunused-variable] int a, b; ^ main.cpp:5:9: warning: unused variable 'b' [-Wunused-variable] int a, b; ^ Non zero exit status: 1