Compilare: user.cpp: In function ‘void add()’: user.cpp:22:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:26:39: 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:51:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:55:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^ user.cpp:75:41: 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:93:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:97:39: 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:119:29: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int i = 0; i < s.size(); ++i ) ^ user.cpp:123:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for( int j = 0; j < graph[nod].size() && !found; ++j ) ^