快读快输 + 快速幂

#define mod 998244353
template <typename T>
inline void read(T & x) {
	T f = 1;
	char c = getchar();
	while (c < '0' || c > '9') {
		if (c == '-') {
			f = -1;
		}
		c = getchar();
	}
	x = 0;
	while (c >= '0' && c <= '9') {
		x = (x << 3) + (x << 1) + c - '0';
		c = getchar();
	}
	x *= f;
}
template <typename T, typename ... Args>
inline void read(T & tmp, Args & ... tmps) {
	read(tmp);
	read(tmps ...);
}
template <typename T>
inline void write(T x) {
    T s[20], top = 0;
    if (x < 0) {
        putchar('-');
        x = ~(x - 1);
    }
    while (x) {
        s[++top] = x % 10;
        x /= 10;
    }
    if (!top) {
        s[++top] = 0;
    }
    while (top) {
        putchar(s[top--] + '0');
    }
}
template <typename T>
inline T quick_pow(T a, T b, T ans = 1) {
	while (b) {
		if (b & 1) {
			ans = ans * a % mod;
		}
		a = a * a % mod;
		b >>= 1;
	}
	return ans;
}