题解 | #素数伴侣#

import sys,math
num1 = int(input().strip())
def just1(a):
    if a == 1:
        return False
    if a == 2:
        return True
    for i in range(2,int(math.sqrt(a))+1):
        if a%i == 0:
            return False
    else:
        return True
def solov(a):
    for j in range(len(list2)):
        if just1(a+list2[j]) and mind[j] == 0:
            mind[j] = 1
            if re[j] == 0 or solov(re[j]):
                re[j] = a
                return True
    else:
        return False

for line in sys.stdin:
    a = map(int,line.strip().split(" "))
    list1,list2,resault = [],[],0
    for i in a:
        if i%2 == 0:
            list1.append(i)
        else:
            list2.append(i)
    re = [0]*len(list2)
    for i in list1:
        mind = [0]*len(list2)
        if solov(i):
            resault +=1
    print(resault)