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func minimumLength(s string) int {
    freq := make([]int, 26)

    for i:=0;i<len(s);i++ {
        freq[s[i] - 'a']++
    }

    ans :=0

    for i:=0;i<26;i++ {
        if freq[i] == 0 {
            continue
        }

        ans++

        if freq[i] % 2 == 0 {
            ans++
        }
    }

    return ans
}