[<n>y][<n>M][<n>w][<n>d][<n>h][<n>m][<n>[s]]
There is a standard syntax for durations that let you easily specify longer periods of time.  A duration consists of one or more "duration parts which are sequences of digits, separated by duration letters.
The valid duration letters are $by$b (for year, or 365 days), $bM$b (for month, or 31 days), $bw$b (for week, or 7 days), $bd$b (for day, or 24 hours), $bh$b (for hour, or 60 minutes), $bm$b (for minute, or 60 seconds), and $bs$b (for second).  We know not all years are 365 days and not all months are 31 days, but we pretend they are for parsing durations.
If the last duration part does not have any letter to indicate the units, seconds are assumed.
$uExamples$u: 1y1M is 365 days plus 31 days; 1y1m is 365 days plus 1 minute; 1h30m45 is ninety minutes and forty-five seconds; and so forth.