Compilare: main.cpp: In function 'int main()': main.cpp:16:21: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( i = 1 ; i <= inp.size () / 3 ; ++ i ) ~~^~~~~~~~~~~~~~~~~~ main.cpp:19:33: warning: comparison between signed and unsigned integer expressions [-Wsign-compare] for ( j = 0 ; j + 2 * i < inp.size () ; ++ j ) ~~~~~~~~~~^~~~~~~~~~~~~ main.cpp:12:17: warning: unused variable 'k' [-Wunused-variable] int i , j , k , ok = 0 , ans = 0 ; ^