%!PS

/p {
    dup dup dup
    4 idiv 4 1 roll
    100 idiv neg 4 1 roll
    400 idiv
    add add add
    7 mod
} bind def

/leapyear {
    dup dup
    4 mod 0 eq {
        100 mod 0 ne exch
        400 mod 0 eq or
        {
            true
        } {
            false
        } ifelse
    } {
        pop pop false
    } ifelse
} bind def

/workdays {
    dup
    p exch
    leapyear {
        7 add
    } if
    [ 0 1 1 1 1 0 0 1 2 2 2 2 1 ] exch get 260 add
} bind def

2021 workdays 260 eq { (Pass) } { (FAIL) } ifelse print ( ) print
2020 workdays 262 eq { (Pass) } { (FAIL) } ifelse =