uses crt;
 
var f,g:text;
    p,n:longint;
function zero(n:longint):longint;
var nr5:longint;
 
begin
    nr5:=0;
    while n<> 0 do
        begin
            nr5:= nr5+ n div 5;
            n:=n div 5;
        end;
    zero:=nr5;
end;
      
function caut(p:longint):longint;
var pas,lim:longint;
 
begin
    pas:=1<<30;
    lim:=0;
    while pas <> 0 do
        begin
            if zero(lim+pas)<p then
                lim:=lim+pas;
            pas:=pas>>1;
        end;
    caut := 1 + lim
end;
begin
    assign(f,'fact.in');
    reset(f);
    assign(g,'fact.out');
    rewrite(g);
    readln(f,p);
    n:=caut(p);
    if zero(n)=p then writeln(g,n)
        else writeln(g,-1);
    close(f);
    close(g);
     
end.