var p,x,i,nr,xx:longint;
    f:text;
begin
assign(f,'fact.in');reset(f);
read(f,p);
close(f);
assign(f,'fact.out');rewrite(f);
if p<0 then write(f,-1)
       else if p=0 then write(f,1)
       else begin
            i:=1;
            nr:=1;
            x:=0;
            while nr<=p do begin
                           x:=5*i;
                           nr:=nr+1;
                           xx:=i;
                           while xx  mod 5=0 do begin
                                               inc(nr);
                                               xx:=xx div 5;
                                               end;
                           i:=i+1;
                           end;
            writeln(f,x);
            end;
close(f);
end.