# Infinite sum of digits

Given an integer

`n`

, you are asked to compute the infinite sum of its digits. We’ll say that the infinite sum of digits is the following process:

- Compute the sum of digits of
`n`

and assign it to`n`

- Repeat that process until
`n`

is a single-digit number

The input contains a single integer

`n`

. The program should print a single integer - the infinite sum of digits of

`n`

.Input | Output |

64 | 1 |

8 | 8 |

**The explanation**for 64: 64 → 6 + 4 = 10 → 1 + 0 = 1 ⇒ 1 is the answer

#### Constraints

Time limit: 2 seconds

Memory limit: 512 MB

Output limit: 1 MB