Compilare: user.cpp: In function ‘int main()’: user.cpp:49:25: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned i = 1; i <= n; i++) ~~^~~~ user.cpp:51:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (unsigned j = 1; j <= m; j++) ~~^~~~ user.cpp:77:12: warning: right operand of comma operator has no effect [-Wunused-value] delete a,b; ^