import kotlin.math.max

fun main() {
    val builder = StringBuilder()

    val n = readInputLine().toInt()
    val aArr = readInputLine().split(" ").map { it.toInt() }.toIntArray()

    // 10の剰余を取った時の最大枚数
    val dp = Array(n + 1) { IntArray(10) { -1 } }

    dp[0][0] = 0

    for ((i, a) in aArr.withIndex()) {
        for (j in 0..9) {
            if (dp[i][j] == -1) {
                continue
            }
            dp[i + 1][j] = max(dp[i + 1][j], dp[i][j])
            dp[i + 1][(j + a) % 10] = max(dp[i + 1][(j + a) % 10], dp[i][j] + 1)
        }
    }

    builder.appendln(dp[n][0])

    print(builder.toString())
}

fun readInputLine(): String {
    return readLine()!!
}