Compilare: main.cpp: In function 'll mask(int, int, int)': main.cpp:7:17: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] return (1 << f - 1) ^ (1 << (f - pref) - 1) ^ (1 << (f - suff) - 1); ~~^~~ main.cpp:7:41: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] return (1 << f - 1) ^ (1 << (f - pref) - 1) ^ (1 << (f - suff) - 1); ~~~~~~~~~~~^~~ main.cpp:7:65: warning: suggest parentheses around '-' inside '<<' [-Wparentheses] return (1 << f - 1) ^ (1 << (f - pref) - 1) ^ (1 << (f - suff) - 1); ~~~~~~~~~~~^~~ main.cpp: In function 'int main()': main.cpp:16:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fft2d.in", "r", stdin); ^ main.cpp:17:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("fft2d.out", "w", stdout); ^