打 codeforces 用的

我目前的级别大概只须要这些：web ll q_pow(ll a, ll b, ll p) { ll ret = 1; for (; b; a = a * a % p, b >>= 1) if (b & 1) ret = ret * a % p; return ret; } ll inv(ll x, ll p) { return q_pow(x, p - 2, p); } int tree[M

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