n = gets.chomp.to_i
a = gets.chomp.split(" ").map(&:to_i)
#動的計画法
INF = Float::INFINITY
dp = Array.new(n+1).map{Array.new(10,-INF)}
dp[0][0] = 0
0.upto(n-1) do |i|
    ichi = a[i] % 10
    0.upto(9) do |j|
        dp[i+1][(j+ichi)%10] = [dp[i][j]+1,dp[i][(j+ichi)%10]].max
    end
end
puts dp[-1][0]