Compilare: user.cpp: In function ‘void build(ll, ll, ll)’: user.cpp:9:52: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] if (st==dr) scanf("%lld %lld",&arb[nod],&t[st]); else ^ user.cpp: In function ‘int main()’: user.cpp:29:30: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("proc2.in","r",stdin); ^ user.cpp:30:32: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("proc2.out","w",stdout); ^ user.cpp:31:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%lld %lld",&n,&m); build(1,1,m); ^