Give me the first day of next month Simple question!

Given a string that contains a date in ISO8601 format, print the first of the next month in ISO8601 format.

Example inputs:

2018-05-06

2019-12-20

Their respective outputs:

2018-06-01

2020-01-01

The rules:


Imports are free and don't count towards your score.
The date will be stored in a string called s.
The solution with the least characters, wins
JavaScript (V8), 67, 57, 56 bytes

-10 thanks to Arnauld,
-1 joining template string and ternary

s=&gt;([a,b]=s.split`-`,+a+!(b%=12))+`-${b++&lt;9?'0'+b:b}-01`


Test cases:



f=s=&gt;([a,b]=s.split`-`,+a+!(b%=12))+`-${b++&lt;9?'0'+b:b}-01`

console.log(f('2018-12-20'))
console.log(f('2019-05-06'))