{遞歸調(diào)用測試}
{功能：對于輸入n,輸出n的階乘}
program sd
var integer s;
    integer t;
procedure factor(integer n;var integer m);
var integer w;
begin
if n=0
then m:=1
else 
  factor(n-1,w);
  m:=n*w
fi
end
begin
read(s);
factor(s,t);
write(t)
end.