Compilare: user.cpp: In function ‘void add(int, Trie*)’: user.cpp:40:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == S.sz()){ ^ user.cpp: In function ‘void del(int, Trie*)’: user.cpp:59:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == S.sz()){ ^ user.cpp: In function ‘int countOcc(int, Trie*)’: user.cpp:69:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == S.sz()){ ^ user.cpp: In function ‘int lcp(int, Trie*, int)’: user.cpp:80:20: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if (pos == S.sz() || node->son[ S[pos]-'a' ] == NULL || node->son[ S[pos]-'a' ]->countPrefix==0){ ^