def sum_digit(x):
    sum = 0
    while(x>0):
        r = x%10
        sum+=r
        x = x // 10
    return sum
    
def sum_list(x):
    sum = 0
    l = len(x)
    for i in range(0,l):
        sum = sum + int(x[i])
    return sum

tc = int(input())

num = 0

x = input()

lis = x.split(" ")

num = int(sum_list(lis))

while(num>9):
    num = sum_digit(num)
    
print(num)