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export default function maxLengthBetweenEqualCharacters(s: string): number {    const firstIndex: number[] = new Array(26).fill(-1);    let maxLength = -1;    for (let i = 0; i < s.length; i++) {        const key = s[i].charCodeAt(0) - "a".charCodeAt(0);        if (firstIndex[key] < 0) {            firstIndex[key] = i;        } else {            maxLength = Math.max(maxLength, i - firstIndex[key] - 1);        }    }    return maxLength;}