Problem:
Score : 400 points

Problem Statement

Snuke has N strings. The i-th string is s_i.

Let us concatenate these strings into one string after arranging them in some order.
Find the maximum possible number of occurrences of AB in the resulting string.

Constraints

1 \leq N \leq 10^{4}

2 \leq |s_i| \leq 10

s_i consists of uppercase English letters.

Input

Input is given from Standard Input in the following format:

N
s_1
\vdots
s_N

Output

Print the answer.

Sample Input 1

3
ABCA
XBAZ
BAD

Sample Output 1

2

For example, if we concatenate ABCA, BAD and XBAZ in this order, the resulting string ABCABADXBAZ has two occurrences of AB.

Sample Input 2

9
BEWPVCRWH
ZZNQYIJX
BAVREA
PA
HJMYITEOX
BCJHMRMNK
BP
QVFABZ
PRGKSPUNA

Sample Output 2

4

Sample Input 3

7
RABYBBE
JOZ
BMHQUVA
BPA
ISU
MCMABAOBHZ
SZMEHMA

Sample Output 3

4

Solution in Kotlin (1.0.0) (judge verdict: Accepted)

fun main(args: Array<String>) {
    val n = readLine()!!.toInt()
    val s = (0 until n).map { readLine()!! }

    var s0 = ""
    val sa = mutableListOf<String>()
    val sb = mutableListOf<String>()
    val sc = mutableListOf<String>()

    for (si in s) {
        when {
            si.first() == 'B' && si.last() == 'A' -> s0 += si
            si.last() == 'A' -> sa.add(si)
            si.first() == 'B' -> sb.add(si)
            else -> sc.add(si)
        }
    }

    var cur = 0
    while (cur < sa.size && cur < sb.size) {
        if (cur == 0) {
            s0 = sa[cur] + s0 + sb[cur]
        } else {
            s0 += sa[cur] + sb[cur]
        }
        cur++
    }

    if (cur < sa.size) {
        s0 = sa.slice(cur until sa.size).joinToString("") + s0
    }

    if (cur < sb.size) {
        s0 += sb.slice(cur until sb.size).joinToString("")
    }

    s0 += sc.joinToString("")

    var ans = 0
    for (i in 1 until s0.length) {
        if (s0[i - 1] == 'A' && s0[i] == 'B') ans++
    }
    println(ans)
}