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Problem Statement

You are given a string S of length N consisting of the characters A, B, and C. Your task is to find the position where the substring "ABC" first appears in S. In other words, find the smallest integer n that satisfies the following conditions:

• $(1 \leq n \leq N - 2)$
• The substring from the $n$-th character to the $(n+2)$-th character of S is "ABC".

If "ABC" does not appear in S, print -1.

Input

The input consists of:

• An integer N $(3 \leq N \leq 100)$ — the length of the string S.
• A string S of length N consisting of the characters A, B, and C.

Output

Print the position where the substring "ABC" first appears in S, or -1 if it does not appear.

Examples

Example 1

8
ABABCABC

3

ABC first appears in $S$ at the $3$-rd through $5$-th characters of $S$. Therefore, the answer is $3$.

Example 2

3
ACB

-1

If ABC does not appear in $S$, print $−1$.

Example 3

20
BBAAABBACAACABCBABAB

13