Compilare: user.cpp: In function ‘void dfs(int, int)’: user.cpp:20:52: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < g[abs(sum - S) % mod].size(); i++) ^ user.cpp:27:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < g[abs(sum) % mod].size(); i++) ^ user.cpp:36:37: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < v[nod].size(); i++) ^ user.cpp:39:48: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i = 0 ; i < g[abs(sum) % mod].size(); i++) ^