Compilare: user.cpp:5:0: warning: "ULLONG_MAX" redefined [enabled by default] #define ULLONG_MAX LLONG_MAX-5+LLONG_MAX ^ In file included from /usr/lib/gcc/i686-linux-gnu/4.8/include-fixed/limits.h:168:0, from /usr/lib/gcc/i686-linux-gnu/4.8/include-fixed/syslimits.h:7, from /usr/lib/gcc/i686-linux-gnu/4.8/include-fixed/limits.h:34, from /usr/include/c++/4.8/climits:41, from /usr/include/i386-linux-gnu/c++/4.8/bits/stdc++.h:39, from user.cpp:4: /usr/include/limits.h:139:0: note: this is the location of the previous definition # define ULLONG_MAX (LLONG_MAX * 2ULL + 1) ^ user.cpp: In function ‘int main()’: user.cpp:11:36: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker3.in","r",stdin); ^ user.cpp:12:38: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("hacker3.out","w",stdout); ^ user.cpp:13:19: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&n); ^ user.cpp:16:32: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%llu%llu",&a,&b); ^