20250910

# def f(x):
#     q=0
#     if x==1:
#         return 0
#     for j in range(2,x):
#         if x%j==0:
#             q=1 #나누어 떨어지면 q=0
#     if q==1:
#         return 0
#     else:
#         return 1
# m=input()
# n=input()
# m=int(m)
# n=int(n)
# sum=0
# min=10007
# for i in range(m,n+1):
#   if f(i)==1:
#     sum=sum+i
#     #print(i)
#     if i<min:
#         min=i
# if sum==0:
#   print("-1")
#   exit()
# print(sum,min,sep="\n")

# n=int(input())
# def f(x):
#     sum=0
#     num=x
#     while True:
#         sum=sum+num%10
#         num=num/10
#         if x<=9:
#             return x
# print(f(n))

n=int(input())
def f(x):
    sum=0
    num=x
    while True:
        sum=sum+num%10
        num=num/10
        if num
        return sum
while True:
    f(n)
    print(f(n))