Compilare: main.cpp: In function 'int main()': main.cpp:33:7: warning: unused variable 'inf' [-Wunused-variable] int inf = (1 << f) - 1; ^~~ main.cpp:24:34: 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:25:36: 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); ^ main.cpp:28:24: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &f, &k); ^ main.cpp:30:36: warning: ignoring return value of 'int scanf(const char*, ...)', declared with attribute warn_unused_result [-Wunused-result] scanf("%d%d", &v[i].r, &v[i].c); ^