1 #include
      
        2 long long arr[21]; 3 long long c(int a,int b) 4 { 5     long long i,sum=1,j; 6     for (i=a,j=1;i>=a-b+1,j<=b;i--,j++) sum=sum*i/j; 7     return sum; 8 } 9 void func()10 {11     int i;12     arr[1]=0;arr[2]=1;13     for(i=3;i<=26;i++)14         arr[i]=(i-1)*(arr[i-1]+arr[i-2]);15 }16 int main(){17     int n;18     while(scanf("%d",&n)!=EOF&&n!=0){19         int h=n/2,i;20         long long ans=0;21         func();22         for(i=2;i<=h;i++){23             ans+=c(n,i)*arr[i];24             //printf("%I64d %I64d\n",c(n,i),arr[i]);25         }26 27         ans++;28         printf("%I64d\n",ans);29     }30     return 0;31 }