#include?<stdlib.h>
int?jiecheng(int?num)
{
int?t?=?num;
while(num?>?1)
{
t?*=?--num;
}
return?t;
}
int?main(int?argc,?char?**?argv)
{
float?e?=?1.0,?n?=?0;
int?f?=?1;
while((n?=?(float)1/jiecheng(f++))?>?0.000001)?
{
e?+=?n;
}
printf("%6lf",?e);
return?0;
}