Program gfsd; Var s,w:String; x,d:Byte; Begin Write('Vvedite stroky'); Readln(s); w:=''; x:=2; While x d:=2; While (x Mod d<>0) And (d<=Sqrt(x)) Do d:=d+1; If d>Sqrt(x) Then w:=w+s[x]; x:=x+1 End; Writeln(w) End.