#pragma GCC optimize("Ofast") #pragma GCC target("avx2") char wbuf[1<<25]; int main(){ char*mmap(); char*rp=mmap(0l,1l<<25,1,2,0,0ll); char*wp=wbuf; long f=0; long c; while(*rp++!='\n'){ } while(c=*rp++){ if(c=='\n'){ if(!f){ *wp++='0'; } *wp++=c; f=0; } if(c>'0'){ f=1; } if(f){ *wp++=c; } } write(1,wbuf,wp-wbuf); _exit(0); }