Compilare: user.cpp: In function ‘void unu()’: user.cpp:40:9: warning: unused variable ‘u’ [-Wunused-variable] ull u=2; ^ user.cpp: In function ‘char recursiv(long long unsigned int)’: user.cpp:61:11: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(n<=k) ^ user.cpp:68:26: warning: for increment expression has no effect [-Wunused-value] for(int z=4;x>=n;z){x/=z;} ^ user.cpp:168:1: warning: control reaches end of non-void function [-Wreturn-type] } ^