Compilare: main.cpp:6:0: warning: "NULL" redefined #define NULL 0 In file included from /usr/include/uchar.h:29:0, from /usr/include/c++/6/cuchar:53, from /usr/include/x86_64-linux-gnu/c++/6/bits/stdc++.h:59, from main.cpp:1: /usr/lib/gcc/x86_64-linux-gnu/6/include/stddef.h:403:0: note: this is the location of the previous definition #define NULL __null main.cpp: In function 'int main()': main.cpp:19:65: warning: suggest parentheses around '+' inside '<<' [-Wparentheses] gcd = __gcd (__gcd (__gcd (rmq [k - 1][i][j], rmq [k - 1][i + 1 << (k - 1)][j]), rmq [k - 1][i][j + 1 << (k - 1)]), rmq [k - 1][i + 1 << (k - 1)][j + 1 << (k - 1)]); ~~^~~ main.cpp:19:103: warning: suggest parentheses around '+' inside '<<' [-Wparentheses] gcd = __gcd (__gcd (__gcd (rmq [k - 1][i][j], rmq [k - 1][i + 1 << (k - 1)][j]), rmq [k - 1][i][j + 1 << (k - 1)]), rmq [k - 1][i + 1 << (k - 1)][j + 1 << (k - 1)]); ~~^~~ main.cpp:19:135: warning: suggest parentheses around '+' inside '<<' [-Wparentheses] gcd = __gcd (__gcd (__gcd (rmq [k - 1][i][j], rmq [k - 1][i + 1 << (k - 1)][j]), rmq [k - 1][i][j + 1 << (k - 1)]), rmq [k - 1][i + 1 << (k - 1)][j + 1 << (k - 1)]); ~~^~~ main.cpp:19:153: warning: suggest parentheses around '+' inside '<<' [-Wparentheses] gcd = __gcd (__gcd (__gcd (rmq [k - 1][i][j], rmq [k - 1][i + 1 << (k - 1)][j]), rmq [k - 1][i][j + 1 << (k - 1)]), rmq [k - 1][i + 1 << (k - 1)][j + 1 << (k - 1)]); ~~^~~