以下程序的功能是计算s=0!+1!+2!+3!+...+n!。请填空。longf(intn){inti;longs;s=_____;for(i=1;i<=n;i++)s=_____;returns;}main(){longs;intk,n;scanf("%d",&n);s=_____;for(k=0;k<=n;k++)s=s+_____;printf("%ld\\n",s);}