var
p,i,aux,exp:int64;
f,g:text;
begin
        assign(f,'factorial.in');reset(F);
        ASSIGN(G,'factorial.out');rewrite(g);
        readln(f,p);
        if p=0 then writeln(g,1);
        exp:=0;
        i:=0;
        while exp<p do begin
              i:=I+5;
              aux:=i;
              while aux mod 5=0 do begin
                aux:=aux div 5;
                inc(exp);
              end;
        end;
        if exp>p then writeln(g,-1)
        else writeln(g,i);
        close(F);
        close(g);
end.