INT(1,50,k) NEWLINE
REP(k)
    # Read the characters into an array until we hit a SPACE.
    REGEX("[a-z]", val)
    SET(alphabet[0]=val)
    WHILEI(i,val!=" ")
        REGEX("[a-z ]", val)
        IF (val!=" ")
            SET(alphabet[i+1]=val)
        END
    END
    # Make sure the characters in the alphabet are unique.
    ASSERT(UNIQUE(alphabet))
    # Read characters until we hit another SPACE.
    # Each character must be in the alphabet.
    REGEX("[a-z]",val)
    ASSERT(INARRAY(val,alphabet))
    WHILEI(i,val!=" ")
        REGEX("[a-z ]",val)
        IF (val!=" ")
            ASSERT(INARRAY(val,alphabet))
        END
        ASSERT(i<=500)
    END
    # Read characters until we hit a NEWLINE.
    # Each character must be in the alphabet
    REGEX("[a-z]",val)
    ASSERT(INARRAY(val,alphabet))
    WHILEI(i,val!="\n")
        REGEX("[a-z\n]",val)
        IF (val!="\n")
            ASSERT(INARRAY(val,alphabet))
        END
        ASSERT(i<=500)
    END
    # Clear the alphabet for the next iteration.
    UNSET(alphabet)
END
# https://github.com/DOMjudge/checktestdata
# https://github.com/DOMjudge/checktestdata/blob/main/doc/format-spec.md
#
# Quick reference:
#
# integer  := 0|-?[1-9][0-9]*
# float    := -?[0-9]+(\.[0-9]+)?([eE][+-]?[0-9]+)?
# string   := ".*"
# varname  := [a-z][a-z0-9]*
# variable := <varname> | <varname> '[' <expr> [',' <expr> ...] ']'
# value    := <integer> | <float> | <string> | <variable> | <function>
# compare  := '<' | '>' | '<=' | '>=' | '==' | '!='
# logical  := '&&' | '||'
# expr     := <term> | <expr> [+-] <term>
# term     := <factor> | <term> [*%/] <factor>
# factor   := <value> | '-' <factor> | '(' <expr> ')' | <factor> '^' <factor>
# test     := '!' <test> | <test> <logical> <test> | '(' <test> ')' | <expr> <compare> <expr> | <testcommand>
#
# Commands:
#
# MATCH(<value> str)
# ISEOF
# UNIQUE(<varname> a [,<varname> b ...])
# INARRAY(<value> val, <varname> var)
# STRLEN(<value> str)
# SPACE / NEWLINE
# EOF
# INT(<expr> min, <expr> max [, <variable> name])
# FLOAT(<expr> min, <expr> max [, <variable> name [, option]])
# FLOATP(<expr> min, <expr> max, <value> mindecimals, <value> maxdecimals, [, <variable> name [, option]])
# STRING(<value> str)
# REGEX(<value> str [, <variable> name])
# ASSERT(<test> condition)
# SET(<variable> name '=' <expr> value[, ...])
# UNSET(<varname> a [,<varname> b ...])
# REP(<expr> count [,<command> separator]) [<command>...] END
# REPI(<variable> i, <expr> count [,<command> separator]) [<command>...] END
# WHILE(<test> condition [,<command> separator]) [<command>...] END
# WHILEI(<variable> i, <test> condition [,<command> separator]) [<command>...] END
# IF(<test> cond) [<command> cmds1...] [ELSE [<command> cmds2...]] END