#!/usr/bin/env bash

main() {
    hour=$(date +%-H)
    if ((hour >= 12 && hour < 16)); then
        printf "%s AM\n" "$(date '+%I:%M:%S')"
    elif ((hour >= 16 || hour <= 23)); then
        printf "%s PM\n" "$(date '+%I:%M:%S')"
    else
        echo "Invalid hour. Please check your system clock."
    fi
}

main