Program nume;
var f,g:text;
p,cifre5:longint;
i:integer;
function impartire5(a:integer):integer;
var nr:integer;
begin
nr:=0;
while (a mod 5=0) do
begin
a:=a div 5;
nr:=nr+1;
end;
impartire5:=nr;
end;
begin
assign (f,'fact.in');
reset (f);
assign (g,'fact.out');
rewrite (g);
read (f,p);
if (p=0) then
write (g,1)
else
begin
cifre5:=0;
i:=5;
while (cifre5<p) do
begin
cifre5:=cifre5+impartire5(i);
i:=i+5;
end;
write (g,i-5);
end;
close (f);
close (g);
end.