stone_blocks() {
    local -n _h="$1"
    local -a _height
    local _index=0 _blocks=0
    local _i
    for _i in "${_h[@]}"; do
        while (( _index > 0 && _height[_index-1] > _i )); do
            ((_index--))
        done
        if (( _index > 0 && _height[_index-1] == _i )); then
            continue
        fi
        _height[_index]=$_i
        ((_blocks++))
        ((_index++))
    done
    echo "$_blocks"
}