Compilare: main.cpp:1:2: warning: #import is a deprecated GCC extension [-Wdeprecated] #import <fstream> ^~~~~~ main.cpp:2:6: warning: ISO C++ forbids declaration of 'main' with no type [-Wreturn-type] main(){std::fstream c("clasic.in");std::ofstream o("clasic.out");int N,i=2,S,x;for(c>>N;i--;S=0){c>>N;for(int j=0;j<N;j++)c>>x,S=S^x;o<<S<<"\n";}} ^