Compilare: user.cpp: In function ‘int main()’: user.cpp:30:31: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for(j=0;j<v[nr].size();++j) a[v[nr][j]]^=1; ^ user.cpp:11:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aprindere.in","r",stdin); ^ user.cpp:12:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("aprindere.out","w",stdout); ^ user.cpp:14:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&n,&m); ^ user.cpp:15:41: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] for(i=1;i<=n;++i) scanf("%d",&a[i]); ^ user.cpp:19:44: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&cam,&cost[i],&nrr); ^ user.cpp:22:47: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&nr), v[i].push_back(nr+1); ^