#include <bits/stdc++.h>
//0 qian j ge
//1 hou j ge
#define INF 0x3f3f3f3f
int N,L,va[8009],c[8009],la[8009][8009],vc[109][109][109][2];
std::vector<int> t[8009];
int sv(int n,int x,int y,int op) {
	if(vc[n][x][y][op]!=-1) {
		return vc[n][x][y][op];
	}
	if(n==N-1) {
		if(x<c[n]&&(x-y)<va[n+1]) return INF;
		return x;
	}
	int ans=INF;
	for(int xx=0;xx<=c[n+1];xx++) {
		int l1=0,l2=0;
		if(xx<c[n+1]) l2=t[n+1][xx+1]-1;else l2=L;
		if(x<c[n]) l1=t[n][x+1]-1;else l1=L;
		int lim=std::min(l1,l2);
		int tp1=la[lim][n],tp2=la[lim][n+1];
		for(int yy=0;yy<=xx;yy++) {
			int vv=va[n+1];
			if(op==1) vv-=std::min(x-y,tp1);
			else vv-=(std::max(std::min(x,tp1),y)-y);			
			int vt=vv-std::min(yy,tp2);
			if((vt>=0)&&((xx==c[n+1]&&x==c[n])||(vt==0))) {
				ans=std::min(ans,sv(n+1,xx,yy,0)+x);				
			}
			vt=vv;
			vt-=std::max(std::min(xx,tp2),xx-yy)-(xx-yy);
			if((vt>=0)&&((xx==c[n+1]&&x==c[n])||(vt==0))) {
				ans=std::min(ans,sv(n+1,xx,yy,1)+x);				
			}
		}
	}
	return vc[n][x][y][op]=ans;
}
signed main(void) {
	memset(vc,-1,sizeof(vc));
	scanf("%d",&N);
	for(int i=1;i<=N;i++) {
		scanf("%d",&va[i]);
		t[i].push_back(0);
	}
	scanf("%d",&L);
	int anss=0;
	for(int i=1;i<=L;i++) {
		int x;
		scanf("%d",&x);
		if(va[x+1]) {
			va[x+1]--;
		} else if(va[x]) {
			va[x]--;
		} else {
			anss++;
		}
		t[x].push_back(i);
		c[x]++;
		for(int j=1;j<=N;j++) {
			la[i][j]=la[i-1][j];
		}
		la[i][x]=t[x].size()-1;
	}
	printf("%d",anss);
	return 0;
	int ans=0x3f3f3f3f;
	for(int i=0;i<=c[1];i++) {
		for(int j=0;j<=i&&j<=va[1];j++) {
			if((i==c[1])||(j==va[1])) ans=std::min(ans,sv(1,i,j,0));
			if((i==c[1])||(j==va[1])) ans=std::min(ans,sv(1,i,j,1));
		}
	}
//	printf("%d\n",sv(4,0,0,0));
	printf("%d",L-ans);
}