program infoarena_factorial;
var p,n,m,k,i,j,nrz:longint;


begin
assign(input,'fact.in');
reset(input);
readln(p);
close(input);

k:=p*5;
i:=5;
j:=trunc(k/i);
nrz:=0;

while j>0 do
begin
nrz:=nrz+j;
i:=i*5;
j:=trunc(k/i);
end;


while nrz>p do
begin
m:=k;

repeat
m:=m div 5;
nrz:=nrz-1;
until m mod 5 <> 0;

k:=k-5;
end;

assign(output,'fact.out');
rewrite(output);
if nrz<p then writeln('-1')
 else if k=0 then writeln('1')
  else writeln(k);
close(output);
end.