C++ :

#define MAXN 1010UL
#define MAXB 100UL
#define B(a) (a+1)

#include <cstdio>
#include <cstring>

inline int MAX(int a,int b){
	return a>b?a:b;
}

struct BigNum{
	int s[MAXB];
	inline void clr(){memset(s,0,sizeof(s));return;}
	inline void prx(){printf("%d",s[s[0]]);for(int i=s[0]-1;i>0;i--) printf("%08d",s[i]);return;}
	inline void setnum(int p){while(p) s[++s[0]]=p%10,p/=10;return;}
	friend BigNum operator + (BigNum temp_a,BigNum temp_b){
		if(!temp_a.s[0]) return temp_b;
		if(!temp_b.s[0]) return temp_a;
		BigNum temp_c;temp_c.clr();
		int i,j,*a=temp_a.s,*b=temp_b.s,*c=temp_c.s;
		c[0]=MAX(a[0],b[0])+1;
		for(i=1;i<c[0];i++){
			c[i]+=a[i]+b[i];
			if(c[i]>99999999) c[i]-=100000000,++c[i+1];
		}
		while(!c[c[0]]&&c[0]>1) --c[0];
		return temp_c;
	}
};

BigNum f[MAXN][MAXN];
int n,s[MAXN],p[MAXN];
bool ex[MAXN<<1];

int main(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d",&s[i]),ex[s[i]]=true;
	for(int i=1;i<=n;i++) scanf("%d",&p[i]),ex[p[i]]=true;
	f[B(0)][B(0)].setnum(1);
	for(int i=1;i<=n;i++){
		for(int j=0;j<=n;j++){
			//h-1 i+1 num=i+j  0<=j<=i-1
			if(i-1>=j) if((ex[i+j]&&s[i]==i+j)||((!ex[i+j])&&(!s[i]))) f[B(i)][B(j)]=f[B(i)][B(j)]+f[B(i-1)][B(j)];
			//h-2 j+1 num=i+j   j<=i<=n
			if(i>=j)   if((ex[i+j]&&p[j]==i+j)||((!ex[i+j])&&(!p[j]))) f[B(i)][B(j)]=f[B(i)][B(j)]+f[B(i)][B(j-1)];
			//printf("%d %d->\n",i,j);
			//f[B(i)][B(j)].prx();
		}
	}
	f[B(n)][B(n)].prx();
	return 0;
}