function abbreviation(a, b, i = a.length - 1, j = b.length - 1, dp = {}) {
    if (j < 0) return 'YES';
    if (i < 0) return 'NO';

    const k = `${i}-${j}`;
    if (!dp[k]) {
        const c1 = a[i];
        const c2 = b[j];
        const isCap = c1 < 'a';

        dp[k] = c1.toUpperCase() === c2
            && abbreviation(a, b, i - 1, j - 1, dp) === 'YES'
            ||
            !isCap
            && abbreviation(a, b, i - 1, j, dp) === 'YES'
            ? 'YES'
            : 'NO';
    }
    return dp[k];
}