#!/bin/sh

! eq $# 2 && printf "Usage: $0 [base] [exponent]\n" >/dev/stderr && exit 1

! stris int "$1" && printf -- "%b: %b: Not an integer\n" "$0" "$1" >/dev/stderr && exit 1
! stris int "$2" && printf -- "%b: %b: Not an integer\n" "$0" "$2" >/dev/stderr && exit 1

base=$1
exponent=$2

result=1

while gt $exponent 0; do
	result=$(multiply $result $base)
	exponent=$(-- $exponent)
done

if ! eq $result $(abs $result) && eq $base $(abs $base); then
	printf "$0: Result is unexpectedly negative, possible integer overflow\n" >/dev/stderr && exit 1
elif eq $result 0 && ! eq $base 0; then
	printf "$0: Result is unexpectedly zero, possible integer overflow\n" >/dev/stderr && exit 1
else
	printf "%b\n" $result
fi

exit 0