Compilare: user.cpp: In function ‘void DFS(int)’: user.cpp:35:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a[k].size(); ++i) ^ user.cpp: In function ‘void DFS2(int, int)’: user.cpp:47:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0; i<a2[k].size(); ++i) ^ user.cpp: In function ‘void Solve()’: user.cpp:56:24: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(i=0; i<cc.size(); i++ ) ^ user.cpp:54:11: warning: unused variable ‘nod’ [-Wunused-variable] int i,nod; ^ user.cpp: In function ‘void R()’: user.cpp:13:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("2sat.in","r",stdin); ^ user.cpp:14:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:18:28: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^ user.cpp: In function ‘int main()’: user.cpp:81:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("2sat.out","w",stdout); ^