import java.io.InputStream; import java.io.IOException; import java.io.PrintWriter; import java.util.ArrayDeque; import java.util.ArrayList; import java.util.Arrays; import java.util.BitSet; import java.util.Comparator; import java.util.Deque; import java.util.HashMap; import java.util.HashSet; import java.util.InputMismatchException; import java.util.Map; import java.util.PriorityQueue; import java.math.BigDecimal; import java.math.BigInteger; public class Main{ static final InputStream in=System.in; static final PrintWriter out=new PrintWriter(System.out); static final int INF=Integer.MAX_VALUE; static final long LINF=Long.MAX_VALUE/2; static int N,M,ans; static int[] A,B; static int[][] dp=new int[21][1<<20]; public static void main(String[] args) throws IOException{ InputReader ir=new InputReader(in); N=ir.nextInt(); A=ir.nextIntArray(N); M=ir.nextInt(); B=ir.nextIntArray(M); Arrays.sort(B); for(int i=0;i<=M;i++){ Arrays.fill(dp[i],INF); dp[i][(1<=0;i--){ for(int j=(1<=0;j--){ dp[i+1][j]=dp[i][j]; for(int k=(1<=1;k--){ if((j&k)!=0) continue; int sum=0; for(int l=0;ldp[i][j|k]+1) dp[i+1][j]=dp[i][j|k]+1; } } } ans=dp[M][0]; out.println(ans==INF?-1:ans); out.flush(); } static class InputReader { private InputStream in; private byte[] buffer=new byte[1024]; private int curbuf; private int lenbuf; public InputReader(InputStream in) {this.in=in;} public int readByte() { if(lenbuf==-1) throw new InputMismatchException(); if(curbuf>=lenbuf){ curbuf= 0; try{ lenbuf=in.read(buffer); } catch (IOException e) { throw new InputMismatchException(); } if(lenbuf<=0) return -1; } return buffer[curbuf++]; } public boolean isSpaceChar(int c){return !(c>=33&&c<=126);} private int skip() {int b; while((b = readByte())!=-1&&isSpaceChar(b)); return b;} public String next() { int b=skip(); StringBuilder sb=new StringBuilder(); while(!isSpaceChar(b)){ sb.appendCodePoint(b); b=readByte(); } return sb.toString(); } public int nextInt() { int c=readByte(); while (isSpaceChar(c)) c=readByte(); boolean minus=false; if (c=='-') { minus=true; c=readByte(); } int res=0; do{ if(c<'0'||c>'9') throw new InputMismatchException(); res=res*10+c-'0'; c=readByte(); }while(!isSpaceChar(c)); return (minus)?-res:res; } public long nextLong() { int c=readByte(); while (isSpaceChar(c)) c=readByte(); boolean minus=false; if (c=='-') { minus=true; c=readByte(); } long res = 0; do{ if(c<'0'||c>'9') throw new InputMismatchException(); res=res*10+c-'0'; c=readByte(); }while(!isSpaceChar(c)); return (minus)?-res:res; } public double nextDouble(){return Double.parseDouble(next());} public BigInteger nextBigInteger(){return new BigInteger(next());} public int[] nextIntArray(int n){ int[] a=new int[n]; for(int i=0;i