Compilare: user.cpp: In function ‘void back(int, int)’: user.cpp:15:36: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int i=0;i<v[nod].size();++i) ^ user.cpp:18:32: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (int j=0;j<v[nod].size();++j) ^ user.cpp: In function ‘int main()’: user.cpp:32:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ciclu2.in","r",stdin); ^ user.cpp:33:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("ciclu2.out","w",stdout); ^ user.cpp:34:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:36:87: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y),v[x].push_back(y),v[y].push_back(x),mat[x][y]=mat[y][x]=1; ^ user.cpp:37:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&m); ^ user.cpp:40:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&x,&y); ^