Compilare: user.cpp: In function ‘int main()’: user.cpp:13:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fold.in","r",stdin); ^ user.cpp:14:35: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("fold.out","w",stdout); ^ user.cpp:18:25: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d %d",&n,&m); ^ user.cpp:26:27: warning: ignoring return value of ‘int scanf(const char*, ...)’, declared with attribute warn_unused_result [-Wunused-result] scanf("%d",&x); ^ cc1plus: warning: iteration 251u invokes undefined behavior [-Waggressive-loop-optimizations] user.cpp:20:5: note: containing loop for( i = 1; i <= 256; ++i ) ^