#define LL long long

 #include<iostream>

 #include<algorithm>

 #include<cstring>

 #include<iomanip>

 #include<cstdio>

 using namespace std;

 const int MAXN=;

 const int DLEN=;

 const int WIDE=;

 class BigNum

 {

 public:

     BigNum(){memset(NUM,,sizeof(NUM));LEN=;}

     BigNum(const BigNum &A){memcpy(NUM,A.NUM,sizeof(NUM));LEN=A.LEN;}

     BigNum(int n){memset(NUM,,sizeof(NUM));NUM[]=n;LEN=;while(NUM[LEN-]>=WIDE){NUM[LEN]+=NUM[LEN-]/WIDE;NUM[LEN-]%=WIDE;LEN++;}}

     LL NUM[MAXN],LEN;

 };

 void Output(const BigNum T)

 {

     cout<<T.NUM[T.LEN-];

     for(int i=T.LEN-;i>=;i--)

     {

         cout.width(DLEN);

         cout.fill('');

         cout<<T.NUM[i];

     }

 }

 BigNum Mult(BigNum A,int n)

 {

     BigNum C(A);

     int i,tmp,k=;

     for(i=;i<C.LEN||k;i++)

     {

         tmp=C.NUM[i]*n+k;

         k=tmp/WIDE;

         C.NUM[i]=tmp%WIDE;

     }

     C.LEN=i;

     return C;

 }

 BigNum Div(BigNum A,int n)

 {

     BigNum C(A);

     int k=;

     for(int i=C.LEN-;i>=;i--)

     {

         k=k*WIDE+C.NUM[i];

         C.NUM[i]=k/n;

         k%=n;

     }

     while(C.NUM[C.LEN-]==) C.LEN--;

     return C;

 }

 int n;

 int a[];

 BigNum A();

 int main()

 {

     freopen("select.in","r",stdin);

     freopen("select.out","w",stdout);

     scanf("%d",&n);

     for(int i=;i<=n;i++)

     {

         int x;

         scanf("%d",&x);

         a[x]++;

     }

     for(int i=;i<=n;i++)

         A=Mult(A,i);

     for(int i=;i<=;i++)

         if(a[i]>)

         {

             for(int j=;j<=a[i];j++)

                 A=Div(A,j);

         }

     Output(A);

     return ;

 }