C++ Fast iostream

/*
 * Author: chhokmah
 * Date: 2020-08-17 21:42:52
 */
#include <bits/stdc++.h>

struct IO {
    const static int size_in = 25 << 20, size_out = 5 << 20;

    char in[size_in], *p_in = in;
    char out[size_out], *p_out = out;

    IO() {
        freopen("test.in", "r", stdin);
        freopen("test.out", "w", stdout);
        fread(in, 1, size_in, stdin);
    }

    ~IO() { fwrite(out, 1, p_out - out, stdout); }

    template <typename T>
    T read() {
        T x = 0;
        bool f = 0;
        while (!isdigit(*p_in)) f |= *p_in++ == '-';
        while (isdigit(*p_in)) x = x * 10 + (*p_in++ & 15);
        return f ? -x : x;
    }

    IO& operator>>(int& x) { return x = read<int>(), *this; }
    IO& operator>>(long long& x) { return x = read<long long>(), *this; }
    IO& operator>>(unsigned long long& x) { return x = read<unsigned long long>(), *this; }
    IO& operator>>(char& ch) { return ch = *p_in++, *this; }

    IO& operator>>(char* s) {
        int n = 0;
        while (*p_in == ' ' || *p_in == '\n' || *p_in == '\0') p_in++;
        while (*p_in != ' ' && *p_in != '\n' && *p_in != '\0') s[n++] = *p_in++;
        return s[n] = '\0', *this;
    }

    template <typename T>
    void write(T x) {
        static char buf[20], *p = buf;
        if (x < 0)
            *p_out++ = '-', x = -x;
        do
            *p++ = '0' + x % 10;
        while (x /= 10);
        while (p != buf) *p_out++ = *--p;
    }

    IO& operator<<(int x) { return write(x), *this; }
    IO& operator<<(long long x) { return write(x), *this; }
    IO& operator<<(unsigned long long x) { return write(x), *this; }
    IO& operator<<(char ch) { return *p_out++ = ch, *this; }
    IO& operator<<(char* s) {
        for (int i = 0; s[i]; ++i) *p_out++ = s[i];
        return *this;
    }
} io;

template <typename T, typename Y>
IO& operator>>(IO& in, std::pair<T, Y>& a) {
    in >> a.first >> a.second;
    return in;
}

template <typename T>
IO& operator>>(IO& in, std::vector<T>& a) {
    for (unsigned i = 0; i < a.size(); ++i) in >> a[i];
    return in;
}

template <typename T>
IO& operator<<(IO& out, std::vector<T> a) {
    for (unsigned i = 0; i < a.size(); ++i) out << a[i] << ' ';
    return out;
}