def kadomatsu original,index
    tmp = []
    3.times{|i|
        tmp.push(original[index[i]])
            }
    if tmp.uniq != tmp || tmp.minmax == [tmp[0],tmp[2]].sort
        return false
    else
        return true
    end
end

def solution kado,rest,count
    tmp = rest.combination(3).to_a.select{|a|kadomatsu(kado,a)}
    if tmp.empty?
        if count % 2 == 0
            return false
        else
            return true
        end
    else
        tmp.each{|w|
            unless solution(kado,rest - w,count + 1)
                return false
            end
            }
        return true
    end
end

n = gets.to_i
k = gets.split.map(&:to_i)
range = [*0..n-1]
kado = range.combination(3).to_a.select{|a|kadomatsu(k,a)}
if kado.empty?
    puts -1
    exit
end
kado.each{|v|
    if solution(k,range - v,1)
        puts v.join(' ')
        exit
    end
    }
puts -1