1 #include<iostream>
 2 #include<cstring>
 3 #include<cstdio>
 4 using namespace std;
 5 struct bign{
 6     int a[1005],len;
 7     bign():len(1){memset(a,0,sizeof(a));}
 8     bign(const char *s){*this=s;}
 9     bign(const int &x){*this=x;}
10     inline void operator=(const char *s){
11         len=strlen(s);
12         for(int i=0;i<len;++i)
13             a[i]=s[len-i-1]-‘0‘;
14     }
15     inline void operator=(const int &x){
16         char s[1005];
17         memset(s,0,sizeof(s));
18         sprintf(s,"%d",x);
19         *this=s;
20     }
21     inline void clear(){while(len>1&&!a[len-1])--len;}
22     inline bign operator+(const bign &x){
23         bign ret;
24         ret.len=max(len,x.len)+1;
25         int jw(0);
26         for(int i=0;i<len;++i){
27             ret.a[i]=a[i]+x.a[i]+jw;
28             jw=ret.a[i]/10;
29             ret.a[i]%=10;
30         }
31         if(jw)
32             ret.a[len++]=jw;
33         ret.clear();
34         return ret;
35     }
36     inline void operator+=(const bign &x){*this=*this+x;}
37     inline bign operator-(const bign &x){
38         bign ret;
39         ret=*this;
40         for(int i=0;i<len;++i){
41             if(ret.a[i]<x.a[i])
42                 ret.a[i]+=10,--ret.a[i+1];
43             ret.a[i]=ret.a[i]-x.a[i];
44         }
45         ret.clear();
46         return ret;
47     }
48     inline void operator-=(const bign &x){*this=*this-x;}
49     inline bign operator-(const int &x){
50         bign tmp(x);
51         return *this-tmp;
52     }
53     inline void operator-=(const int &x){*this=*this-x;}
54     inline bign operator*(const bign &x){
55         bign ret;
56         ret.len=len+x.len+1;
57         int jw;
58         for(int i=0;i<len;++i){
59             jw=0;
60             for(int j=0;j<x.len;++j){
61                 ret.a[i+j]+=a[i]*x.a[j]+jw;
62                 jw=ret.a[i+j]/10;
63                 ret.a[i+j]%=10;
64             }
65             ret.a[i+x.len]+=jw;
66         }
67         ret.clear();
68         return ret;
69     }
70     inline void operator*=(const bign &x){*this=*this*x;}
71     inline bign operator*(const int &x){
72         bign tmp(x);
73         return *this*tmp;
74     }
75     inline void operator*=(const int &x){*this=*this*x;}
76     inline void print(){
77         for(int i=len-1;i>=0;--i)
78             printf("%d",a[i]);
79     }
80 }f[205];
81 int n;
82 int main(){
83     scanf("%d",&n);
84     f[0]=1;
85     f[1]=0;
86     for(int i=2;i<=n;++i)
87         f[i]=(f[i-1]+f[i-2])*(i-1);
88     f[n].print();
89 }