program giaithua;
uses crt;
var x,gt:int64;
n,i:byte;
begin
clrscr;
write('Nhap x: '); readln(x);
n:=1; gt:=1;
while gt<x do
begin
n:=n+1;
gt:=1;
for i:=1 to n do
gt:=gt*i;
end;
if gt=x then write('Co 1 so la: ',n)
else write('Khong co');
readln
end.