Compilare: main.cpp: In function 'char next_char()': main.cpp:17:32: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] fread(buff,1,val,stdin); ^ main.cpp: In function 'int main()': main.cpp:74:36: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("marbles.in","r",stdin); ^ main.cpp:75:38: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen("marbles.out","w",stdout); ^