Compilare: user.cpp: In function ‘void dfs(int)’: user.cpp:138:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < W[x].size(); ++ i) ^ user.cpp: In function ‘void update(int)’: user.cpp:150:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < W[x].size(); ++ i) ^ user.cpp: In function ‘void solve()’: user.cpp:170:39: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < T[i].size(); ++ j) ^ user.cpp: In member function ‘char InParser::read_ch()’: user.cpp:47:38: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff, 1, 4096, fin); ^