Compilare: user.cpp: In function ‘void add()’: user.cpp:23:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:27:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^ user.cpp: In function ‘void del()’: user.cpp:52:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:56:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^ user.cpp:76:40: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[pnod].size() && !found; ++j ) ^ user.cpp: In function ‘int cnt()’: user.cpp:94:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:98:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^ user.cpp: In function ‘int pref()’: user.cpp:122:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:126:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^