Compilare: user.cpp:2:6: warning: ISO C++ forbids declaration of ‘main’ with no type [-Wreturn-type] main(){int64_t N,P=1;for(std::ifstream("fetite.in")>>N;N/P;P*=2);std::ofstream("fetite.out")<<~-(N-P/2<<1);} ^ user.cpp: In function ‘int main()’: user.cpp:2:99: warning: suggest parentheses around ‘-’ inside ‘<<’ [-Wparentheses] main(){int64_t N,P=1;for(std::ifstream("fetite.in")>>N;N/P;P*=2);std::ofstream("fetite.out")<<~-(N-P/2<<1);} ~^~~~