#! /bin/sh

: 'This file is in the public domain, so clarified as of' : '2006-07-17 by Arthur David Olson.'

case $#-$1 in

2-|2-0*|2-*[!0-9]*)
        echo "$0: wild year - $1" >&2
        exit 1 ;;

esac

case $#-$2 in

2-even)
        case $1 in
                *[24680])                       exit 0 ;;
                *)                              exit 1 ;;
        esac ;;
2-nonpres|2-nonuspres)
        case $1 in
                *[02468][048]|*[13579][26])     exit 1 ;;
                *)                              exit 0 ;;
        esac ;;
2-odd)
        case $1 in
                *[13579])                       exit 0 ;;
                *)                              exit 1 ;;
        esac ;;
2-uspres)
        case $1 in
                *[02468][048]|*[13579][26])     exit 0 ;;
                *)                              exit 1 ;;
        esac ;;
2-*)
        echo "$0: wild type - $2" >&2 ;;

esac

echo “$0: usage is $0 year even|odd|uspres|nonpres|nonuspres” >&2 exit 1