Compilare: user.cpp: In function ‘void read()’: user.cpp:16:24: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d",&N,&M); ^ user.cpp:20:33: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d%d",&a,&b,&c); ^ user.cpp: In function ‘int main()’: user.cpp:67:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.in","r",stdin); ^ user.cpp:68:34: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("apm.out","w",stdout); ^ user.cpp: In function ‘int select()’: user.cpp:35:12: warning: ‘pzmin’ may be used uninitialized in this function [-Wmaybe-uninitialized] return pzmin; ^ user.cpp: In function ‘void prim(int)’: user.cpp:45:20: warning: ‘pzmin’ may be used uninitialized in this function [-Wmaybe-uninitialized] used[k] = 1; ^