Compilare: user.cpp: In function ‘void read(int&)’: user.cpp:15:87: 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(++pos==2000)pos=0,fread(buff,1,2000,stdin); ^ user.cpp:17:113: 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'){nr=nr*10+buff[pos]-'0';if(++pos==2000)pos=0,fread(buff,1,2000,stdin);} ^ user.cpp: In function ‘int main()’: user.cpp:22:33: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.in","r",stdin); ^ user.cpp:23:37: warning: ignoring return value of ‘FILE* freopen(const char*, const char*, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] freopen("custi.out", "w", stdout); ^ user.cpp:24:28: warning: ignoring return value of ‘size_t fread(void*, size_t, size_t, FILE*)’, declared with attribute warn_unused_result [-Wunused-result] fread(buff,1,2000,stdin); ^