RT，这份 fread 有些奇妙问题，使用时会出现不使用文件无法输入，摁按键没有反应，而且甚至有时候读一个 int 需要 $0.5s$，但是我靠它拿到了 Ynoi 的最优解，求助这是什么玄学问题。

namespace io {
const int SIZE = (1 << 21) + 1;
char ibuf[SIZE], *iS, *iT, obuf[SIZE], *oS = obuf, *oT = oS + SIZE - 1, c, qu[55];
int f, qr;
// getchar
#define gc() (iS == iT ? (iT = (iS = ibuf) + fread(ibuf, 1, SIZE, stdin), (iS == iT ? EOF : *iS++)) : *iS++)
// print the remaining part
inline void flush() {
    fwrite(obuf, 1, oS - obuf, stdout);
    oS = obuf;
}
// putchar
inline void putc(char x) {
    *oS++ = x;
    if (oS == oT) flush();
}
// input a signed integer
template <class I>
inline void read(I &x) {
    for (f = 1, c = gc(); c < '0' || c > '9'; c = gc())
        if (c == '-') f = -1;
    for (x = 0; c <= '9' && c >= '0'; c = gc()) x = x * 10 + (c & 15);
    x *= f;
}
// print a signed integer
template <class I>
inline void print(I x) {
    if (!x) putc('0');
    if (x < 0) putc('-'), x = -x;
    while (x) qu[++qr] = x % 10 + '0', x /= 10;
    while (qr) putc(qu[qr--]);
}
struct Flusher_ {
    ~Flusher_() {
        flush();
    }
} io_flusher_;
}  // namespace io
using io ::print;
using io ::putc;
using io ::read;