Compilare: user.cpp: In function ‘void Solve()’: user.cpp:82:16: warning: suggest explicit braces to avoid ambiguous ‘else’ [-Wparentheses] if ( a[i].r == a[j].r ) ^ user.cpp:137:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( size_t i = 0; i < N; ++i ) ^ user.cpp:53:10: warning: unused variable ‘ok’ [-Wunused-variable] bool ok; ^