Compilare: user.cpp: In function ‘int main()’: user.cpp:35:26: warning: unused variable ‘from’ [-Wunused-variable] int e = t.first, from = t.second; ^~~~ user.cpp:36:30: warning: ‘to’ may be used uninitialized in this function [-Wmaybe-uninitialized] int to = x[e] ^ y[e] ^ to; ~~~~~~~~~~~~^~~~