/**************************************************************

     Problem: 1005

     User: Tunix

     Language: C++

     Result: Accepted

     Time:188 ms

     Memory:1304 kb

 ****************************************************************/

 //BZOJ 1005

 #include<cstdio>

 #include<cstring>

 #include<cstdlib>

 #include<iostream>

 #include<algorithm>

 #define rep(i,n) for(int i=0;i<n;++i)

 #define F(i,j,n) for(int i=j;i<=n;++i)

 #define D(i,j,n) for(int i=j;i>=n;--i)

 #define pb push_back

 using namespace std;

 typedef long long LL;

 inline int getint(){

     int r=,v=; char ch=getchar();

     for(;!isdigit(ch);ch=getchar()) if (ch=='-') r=-;

     for(; isdigit(ch);ch=getchar()) v=v*-''+ch;

     return r*v;

 }

 const int N=;

 /*******************template********************/

 struct bint{

     int l,v[];

     bint(){l=; memset(v,,sizeof v);}

     int& operator [] (int x){return v[x];}

 }ans;

 const int Limit=;

 void print(bint a){

     printf("%d",a[a.l]);

     D(i,a.l-,) printf("%03d",a[i]);

     puts("");

 }

 bint operator * (bint a,int p){

     int tmp=;

     F(i,,a.l){

         a[i]=a[i]*p+tmp;

         tmp=a[i]/Limit;

         a[i]%=Limit;

     }

     if (tmp) a[++a.l]=tmp;

     return a;

 }

 int n,a[N],b[N],prime[N],tot,m,cnt;

 bool vis[N];

 void ready(int n){

     F(i,,n){

         if (!vis[i]) prime[++tot]=i;

         F(j,,tot){

             if (i*prime[j]>n) break;

             vis[i*prime[j]]=;

             if (i%prime[j]==) break;

         }

     }

 }

 void add(int k,int v){

     F(j,,tot){

         int x=k;

         while (x){

             b[j]+=x/prime[j]*v;

             x/=prime[j];

         }

     }

 }

 int main(){

 #ifndef ONLINE_JUDGE

     freopen("1005.in","r",stdin);

     freopen("1005.out","w",stdout);

 #endif

     ready();

     n=getint();

     if (n==){

         a[]=getint();

         if (a[]<=) puts("");

         else puts("");

         return ;

     }

     F(i,,n){

         a[i]=getint();

         if (a[i]== || a[i]>n-) {puts(""); return ;}

     }

     F(i,,n){

         if (a[i]>){

             a[i]-=;

             m+=a[i];

         }

         else cnt++;

     }

     if (m>n-){ puts(""); return ;}

     int tmp=n-;

     F(i,,n){

         if (a[i]>){

             add(tmp,);

             add(a[i],-);

             add(tmp-a[i],-);

             tmp-=a[i];

         }

     }

 //  F(i,1,tot) printf("%d ",b[i]); puts("");

     ans[]=;

     F(i,,tot) F(j,,b[i]) ans=ans*prime[i];

     F(j,,tmp) ans=ans*cnt;

     print(ans);

     return ;

 }