Compilare: main.cpp: In function 'int main()': main.cpp:136:18: warning: unused variable 'countX' [-Wunused-variable] int aux, countX; ^~~~~~ main.cpp:75:32: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sec.in", "r", stdin); ^ main.cpp:76:34: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("sec.out", "w", stdout); ^ main.cpp:81:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &T, &c); ^ main.cpp:84:26: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &n, &k); ^ main.cpp:86:25: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d", &a[i]); ^ main.cpp: In function 'void build_exp2()': main.cpp:19:11: warning: iteration 3999998 invokes undefined behavior [-Waggressive-loop-optimizations] l2[i] = l2[i - 1]; ~~~~~~^~~~~~~~~~~ main.cpp:18:21: note: within this loop for (int i = 2; i <= 2 * MAX_N; i++) { ~~^~~~~~~~~~~~