Compilare: main.cpp: In function 'char adv()': main.cpp:3:102: warning: ignoring return value of 'size_t fread(void*, size_t, size_t, FILE*)', declared with attribute warn_unused_result [-Wunused-result] /** parsing **/ const int S=(1<<17);char buf[S];int ptr=S;char adv(){if (ptr==S){fread(buf,1,S,stdin);ptr=0;}return buf[ptr++];} int read(){char c=adv();while (c<'0' || '9'<c)c=adv();int r=0;while ('0'<=c && c<='9'){r=10*r+c-'0';c=adv();}return r;} ^ main.cpp: In function 'int main()': main.cpp:9:30: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("hagi.in","r",stdin);freopen ("hagi.out","w",stdout); ^ main.cpp:9:62: warning: ignoring return value of 'FILE* freopen(const char*, const char*, FILE*)', declared with attribute warn_unused_result [-Wunused-result] freopen ("hagi.in","r",stdin);freopen ("hagi.out","w",stdout); ^