221011

# n = int(input())
# k = input().split()
#
# for i in range(n):
#     k[i] = int(k[i])
#
# for i in range(n):
#     print(str(i+1)+': ', end = '')
#     for j in range(len(k)):
#         if i == j:
#             continue
#         if k[i] < k[j]:
#             print('<', end=' ')
#         elif k[i] > k[j]:
#             print('>', end=' ')
#         else:
#             print('=', end=' ')
#     print()
# count = 0
# data = [1,2,3,4,5,1,2,3,4,1,2,3]
# # for i in range(len(data)):
# #     if data[i] == 1:
# #         count+=1
# #
# # print(count)
#
# print(data.count(1))

# data = 'Hello world'
# print(type(data))
# print(data)
#
# print(data.count('e'))
# data = list(data)
# print(type(data))
# print(data)
# print(data.count('e'))
# data.

# n = input()
# data = n
# print('a:', data.count('a'), sep='')
# print('b:', data.count('b'), sep='')
# print('c:', data.count('c'), sep='')
# print('d:', data.count('d'), sep='')
# print('e:', data.count('e'), sep='')
# print('f:', data.count('f'), sep='')
# print('g:', data.count('g'), sep='')
# print('h:', data.count('h'), sep='')
# print('i:', data.count('i'), sep='')
# print('j:', data.count('j'), sep='')
# print('k:', data.count('k'), sep='')
# print('l:', data.count('l'), sep='')
# print('m:', data.count('m'), sep='')
# print('n:', data.count('n'), sep='')
# print('o:', data.count('o'), sep='')
# print('p:', data.count('p'), sep='')
# print('q:', data.count('q'), sep='')
# print('r:', data.count('r'), sep='')
# print('s:', data.count('s'), sep='')
# print('t:', data.count('t'), sep='')
# print('u:', data.count('u'), sep='')
# print('v:', data.count('v'), sep='')
# print('w:', data.count('w'), sep='')
# print('x:', data.count('x'), sep='')
# print('y:', data.count('y'), sep='')
# print('z:', data.count('z'), sep='')

# x = 'a'
# y = 'z'
# print(x, y)
# x = ord(x)
# y = ord(y)
# print(x, y)

# n = input()
# data = n
# for i in range(97, 123):
#     print(chr(i),':', data.count(chr(i)), sep='')

# import sys
# from PyQt5.QtWidgets import QApplication, QWidget
# import tkinter
#
# class MyApp(QWidget):
#
#     def __init__(self):
#         super().__init__()
#         self.initUI()
#
#     def initUI(self):
#         self.setWindowTitle('My First Application')
#         self.move(300, 300)
#         self.resize(400, 200)
#         self.show()
#
# if __name__ == '__main__':
#    app = QApplication(sys.argv)
#    ex = MyApp()
#    sys.exit(app.exec_())

# n = input()
# data = n
# n = str
# print(data.count('('), data.count(')'))

# 함수: function < factory
# def func(  ):
#     print('Here is Function inside')
#
# # x, y = map(int, input().split())
# func()0
#
# def plus(i):
#     sum = 0
#     return (n)
#     n = input()
#     n = list(n)
#     return (n)
#
#     for i in range(len(n)):
#     sum += i
#     if i > 10:
#         continue
# print()

def plus(k):
    v = str(k)
    sum = 0
    for i in range(10):
        sum += ( i * v.count(chr(i+48)) )
    return sum
n = int(input())

for i in range(10000000):
    n = plus(n)
    if n < 10:
        break

print(n)


# def v(a, b):
#
#     return a+b
#
# print(v(10, 20))

# def calcu(k):
#     s = 0
#     #
#     #
#     #
#     return s
#
# n = int(input())
# x = calcu(n)
#
# print(x)