Compilare: user.cpp: In function ‘void dfs_a(int, int)’: user.cpp:18:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[k].size(); i++) ^ user.cpp: In function ‘void dfs_b(int, int)’: user.cpp:34:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < g[k].size(); i++) ^ user.cpp: In function ‘bool dfs(int)’: user.cpp:58:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < cup[k].size(); i++) ^ user.cpp:68:38: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0 ; i < cup[k].size(); i++) ^ user.cpp: In function ‘int main()’: user.cpp:160:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[x].size(); i++) ^ user.cpp:161:55: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j = 0; j < g[y].size(); j++) ^ user.cpp:173:51: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i = 0; i < v[x].size(); i++) ^