#include<bits/stdc++.h>
#define Gc() getchar()
#define Me(x,y) memset(x,y,sizeof(x))
#define Mc(x,y) memcpy(x,y,sizeof(x))
#define d(x,y) ((m)*(x-1)+(y))
#define R(n) (rnd()%(n)+1)
#define Pc(x) putchar(x)
#define LB lower_bound
#define UB upper_bound
#define fi first
#define se second
#define eb emplace_back
#define all(x) x.begin(),x.end()
using namespace std;using ll=long long;using db=double;using lb=long db;using ui=unsigned;using ull=unsigned long long;using pii=pair<int,int>;
const int N=8000+5,M=300+5,K=1000+5,mod=998244353,Mod=mod-1;const db eps=1e-9;const int INF=1e9+7;mt19937 rnd(28382);
#define Tp template<typename T>
#define Ts template<typename T,typename... Ar>
namespace Debug{
	Tp void _debug(char* f,T t){cerr<<f<<'='<<t<<endl;}
	Ts void _debug(char* f,T x,Ar... y){while(*f!=',') cerr<<*f++;cerr<<'='<<x<<",";_debug(f+1,y...);}
	#ifdef LOCAL
	#define gdb(...) _debug((char*)#__VA_ARGS__,__VA_ARGS__)
	#else 
	#define gdb(...) void()
	#endif
}using namespace Debug;
int n,A[N],m,X[N];
int f[N][N],g[N][N];
int calc(int l,int r){
	if(l==r) return 0;
	for(int i=l;i<=r;i++){
		static int cnt[N];Me(cnt,0);
		for(int j=1;j<=m;j++) if(X[j]==i) cnt[j]++;
		for(int j=1;j<=m+1;j++) cnt[j]+=cnt[j-1];
		if(i==l){
			for(int j=1;j<=m+1;j++) if((X[j]==i||X[j]==i+1||j==m+1)&&cnt[j-1]<=A[i+1]) f[j][A[i+1]-cnt[j-1]]=cnt[j-1];
			continue;
		}
		if(i==r){
			int ans=INF;
			for(int j=1;j<=m+1;j++) if(X[j]==i-1||X[j]==i||j==m+1){
				for(int h=0;h<=m+1;h++) if(f[j][h]<=m){
					if(cnt[j-1]<h){
						if(j>m) ans=min(ans,f[j][h]+cnt[m]);
					}else ans=min(ans,f[j][h]+cnt[j-1]),gdb(j,h,f[j][h]+cnt[j-1]);
				}
			}
			return ans;
		}
		for(int j=1;j<=m+1;j++) if(X[j]==i||X[j]==i-1||j==m+1) Mc(g[j],f[j]),Me(f[j],0x3f);
		int w=INF;
		for(int j=1;j<=m+1;j++) if(X[j]==i-1||X[j]==i||j==m+1){
			for(int h=0;h<=m+1;h++)if(g[j][h]<=m){
				// gdb(j,h,g[j][h],cnt[j-1]);
				if(j>m) w=min(w,g[j][h]+cnt[m]);
				if(cnt[j-1]<h) continue;
				for(int x=1;x<=j;x++) if((X[x]==i||X[x]==i+1||x==m+1)&&min(cnt[x-1],cnt[j-1]-h)<=A[i+1]){
					f[x][A[i+1]-min(cnt[x-1],cnt[j-1]-h)]=min(f[x][A[i+1]-min(cnt[x-1],cnt[j-1]-h)],g[j][h]+cnt[j-1]);
				}
				for(int x=j+1;x<=m+1;x++) if((X[x]==i||X[x]==i+1||x==m+1)&&cnt[x-1]-h<=A[i+1]){
					if(i==1) gdb(j,h,x);
					f[x][A[i+1]-cnt[x-1]+h]=min(f[x][A[i+1]-cnt[x-1]+h],g[j][h]+cnt[x-1]);
				}
			}
		}
		for(int x=1;x<=m+1;x++) if((X[x]==i||X[x]==i+1||x==m+1)&&cnt[x-1]<=A[i+1]) f[x][A[i+1]-cnt[x-1]]=min(f[x][A[i+1]-cnt[x-1]],w);
	}
	return -1;
}
void Solve(){
	scanf("%d",&n);
	for(int i=1;i<=n;i++) scanf("%d",&A[i]);
	scanf("%d",&m);
	for(int i=1;i<=m;i++) scanf("%d",&X[i]);
	for(int i=0;i<=n;i++) X[i+m+1]=i;
	for(int i=1;i<=n;i++) A[i]=min(A[i],m+1);
	Me(f,0x3f);
	int La=0,ans=0;
	for(int i=1;i<=n;i++) if(!A[i]) ans+=calc(La,i-1),La=i;
	ans+=calc(La,n);
	printf("%d\n",m-ans);
}
int main(){
	int t=1;
	// scanf("%d",&t);
	while(t--) Solve();
	cerr<<clock()*1.0/CLOCKS_PER_SEC<<'\n';
}