Compilare: main.cpp:2:0: warning: "ULLONG_MAX" redefined #define ULLONG_MAX 100000000 In file included from /usr/lib/gcc/x86_64-linux-gnu/6/include-fixed/limits.h:168:0, from /usr/lib/gcc/x86_64-linux-gnu/6/include-fixed/syslimits.h:7, from /usr/lib/gcc/x86_64-linux-gnu/6/include-fixed/limits.h:34, from /usr/include/c++/6/climits:42, from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:39, from main.cpp:1: /usr/include/limits.h:137:0: note: this is the location of the previous definition # define ULLONG_MAX (LLONG_MAX * 2ULL + 1) main.cpp: In function 'int cb(long long unsigned int, long long unsigned int)': main.cpp:35:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(NR == n) ~~~^~~~ main.cpp:37:15: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] if(NR < n) ~~~^~~ main.cpp:30:9: warning: unused variable 'OK' [-Wunused-variable] int OK = 0; ^~