const input = await Deno.readTextFile("./input.txt").then(
    (f) =>
        f.split("\n").reduce<[number[], number[]]>(
            (
                acc,
                cur,
            ) => [[...acc[0], +cur.split("   ")[0]], [
                ...acc[1],
                +cur.split("   ")[1],
            ]],
            [[], []],
        ),
).then(([first, second]) => [
    first,
    second.reduce((acc, cur) => {
        if (acc[cur] !== undefined) acc[cur]++;
        else acc[cur] = 1;

        return acc;
    }, {} as Record<number, number>),
]).then(([first, map]) =>
    first.reduce((acc, cur) => acc + ((map[cur] ?? 0) * cur), 0)
);
console.log("Answer = " + input);