Compilare: main.cpp: In function 'int main()': main.cpp:55:33: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("vmin.in","r",stdin); ^ main.cpp:56:35: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("vmin.out","w",stdout); ^ main.cpp:58:17: warning: iteration 8000000 invokes undefined behavior [-Waggressive-loop-optimizations] t[i].in = 0; ~~~~~~~~^~~ main.cpp:57:21: note: within this loop for (int i = 0;i<=sz * 4;i++) { ~^~~~~~~~