Compilare: user.cpp: In function ‘bool pairUp(int)’: user.cpp:58:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<vecin[nod].size();i++){ ^ user.cpp: In function ‘void dfs(int)’: user.cpp:75:35: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(int i=0;i<vecin[nod].size();i++){ ^ user.cpp: In function ‘int main()’: user.cpp:83:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("album.in","r",stdin); ^ user.cpp:84:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen ("album.out","w",stdout); ^ user.cpp:87:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d%d",&n,&k); ^ user.cpp:91:38: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf ("%d",&cls[i].v[j]); ^