Where are they hiding ?

01234567891011121314 012345678910{\color{#3D99F6}111}21314\ldots

The above is the beginning of all non-negative integers concatenated into a single infinite string.

111\color{#3D99F6}111 is the first sub-string with 3 identical digits in a row, with different digits preceding and following the run of the identical digits. The first 1\color{#3D99F6}1 of 111\color{#3D99F6}111 comes at position 13 (from left) in the infinite string.

Where is the first such sub-string with 4 identical digits?

Give the position of the first digit of the four.


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