Compilare: user.cpp: In function ‘bool hopcroft(int)’: user.cpp:15:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[x].size();i++) { ^ user.cpp:23:26: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (i=0;i<v[x].size();i++) { ^ user.cpp: In function ‘int main()’: user.cpp:52:30: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for (j=0;j<v[i].size();j++) { ^ user.cpp:35:39: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("circulatie.in","r",stdin); ^ user.cpp:36:41: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("circulatie.out","w",stdout); ^ user.cpp:38:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:40:29: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&a,&b); ^