Compilare: user.cpp: In function ‘int find_(int)’: user.cpp:19:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<H[h(x)].size() && H[h(x)][i]!=x;i++); ^ user.cpp:20:28: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] return (i<H[h(x)].size()); ^ user.cpp: In function ‘void pop(int)’: user.cpp:30:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<H[h(x)].size();i++) ^