numOfKeys = int(input())
keysTemp = input()
keys = keysTemp.split()
numOfDoors = int(input())
doorsTemp = input()
doors = doorsTemp.split()
days = 0;

for input in keys:
    if int(input) == 1:
        if str(2) in doors:
            days += 1
    elif int(input) == 104:
        if str(103) in doors:
            days += 1
    else:
        for door in doors[:]:
            if int(input) + 1 == int(door) or int(input) - 1 == int(door):
                days += 1
                doors.remove(door)
print(days)