Compilare: user.cpp: In function ‘int main()’: user.cpp:34:37: 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,buff_size, stdin); ^ user.cpp: In function ‘void read(long long int&)’: user.cpp:20:136: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while(buff[pos] < '0' || buff[pos] > '9'){if(buff[pos]== '-' )semn = -1; if(++pos == 200000) fread(buff, 1, 200000, stdin), pos = 0;} ^ user.cpp:22:139: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] while('0' <= buff[pos] && buff[pos] <= '9') {nr = nr * 10 + buff[pos] - '0';if(++pos == 200000) fread(buff, 1, 200000, stdin), pos = 0;} ^