var gaps = [];
var previous = :valid;

ARGF.each { |line|
    var (date, *readings) = line.words...;
    var valid = [];
    var hour = 0;
    readings.map{.to_n}.each_slice(2, { |slice|
        var(reading, flag) = slice...;
        if (flag > 0) {
            valid << reading;
            if (previous == :invalid) {
                gaps[-1]{:end} = "#{date} #{hour}:00";
                previous = :valid;
            }
        }
        else {
            if (previous == :valid) {
                gaps << Hash(start => "#{date} #{hour}:00");
            }
            gaps[-1]{:count} := 0 ++;
            previous = :invalid;
        }
        ++hour;
    })
    say ("#{date}: #{ '%8s' % (valid ? ('%.3f' % Math.avg(valid...)) : 0) }",
         " mean from #{ '%2s' % valid.len } valid.");
}

var longest = gaps.sort_by{|a| -a{:count} }.first;

say ("Longest period of invalid readings was #{longest{:count}} hours,\n",
    "from #{longest{:start}} till #{longest{:end}}.");