Problem:
Score : 400 points

Problem Statement

You are going out for a walk, when you suddenly encounter N monsters. Each monster has a parameter called health, and the health of the i-th monster is h_i at the moment of encounter. A monster will vanish immediately when its health drops to 0 or below.

Fortunately, you are a skilled magician, capable of causing explosions that damage monsters. In one explosion, you can damage monsters as follows:

Select an alive monster, and cause an explosion centered at that monster. The health of the monster at the center of the explosion will decrease by A, and the health of each of the other monsters will decrease by B. Here, A and B are predetermined parameters, and A > B holds.

At least how many explosions do you need to cause in order to vanish all the monsters?

Constraints

All input values are integers.

1 ≤ N ≤ 10^5

1 ≤ B < A ≤ 10^9

1 ≤ h_i ≤ 10^9

Input

Input is given from Standard Input in the following format:

N A B
h_1
h_2
:
h_N

Output

Print the minimum number of explosions that needs to be caused in order to vanish all the monsters.

Sample Input 1

4 5 3
8
7
4
2

Sample Output 1

2

You can vanish all the monsters in two explosion, as follows:

First, cause an explosion centered at the monster with 8 health. The healths of the four monsters become 3, 4, 1 and -1, respectively, and the last monster vanishes.

Second, cause an explosion centered at the monster with 4 health remaining. The healths of the three remaining monsters become 0, -1 and -2, respectively, and all the monsters are now vanished.

Sample Input 2

2 10 4
20
20

Sample Output 2

4

You need to cause two explosions centered at each monster, for a total of four.

Sample Input 3

5 2 1
900000000
900000000
1000000000
1000000000
1000000000

Sample Output 3

800000000

Solution in C++14 (GCC 5.4.1) (judge verdict: Wrong Answer)

#include "bits/stdc++.h"
#define rep(i,b) for(ll i=0;i<b;i++)
#define ll long long
using namespace std;
template<typename T> void SSS(T& t) { cin >> t; }
#define SS(T, ...)      T __VA_ARGS__; SSS(__VA_ARGS__);
#define vl vector<ll>
#define vvl vector<vector<ll>>
#define vvvl vector<vector<vector<ll>>>
#define debug(x) cerr<<#x<<" "<<x<<'\n';
bool cmp(pair<ll,ll> a, pair<ll,ll> b) { return a.second < b.second; }

const int MOD = 1000000007;

template< int MODULO > struct ModInt {
    using int64 = long long;
    using uint32 = unsigned int;
    using uint64 = unsigned long long;
    uint64 x; ModInt() : x(0) {}
    ModInt(int64 y) : x(set(y % MODULO + MODULO)) {}
    static uint64 set(const int64 &y) { return (y < MODULO) ? y : y - MODULO; }
    static ModInt make(const uint64 &y) { ModInt ret = y; return ret; }
    ModInt operator+(const ModInt &m) const { return make(set(x + m.x)); }
    ModInt operator-(const ModInt &m) const { return make(set(x + MODULO - m.x)); }
    ModInt operator*(const ModInt &m) const { return make(x * m.x % MODULO); }
    ModInt operator/(const ModInt &m) const { return make(x) * ~make(m.x); }
    ModInt &operator+=(const ModInt &m) { return *this = *this + m; }
    ModInt &operator-=(const ModInt &m) { return *this = *this - m; }
    ModInt &operator*=(const ModInt &m) { return *this = *this * m; }
    ModInt &operator/=(const ModInt &m) { return *this = *this / m; }
    ModInt &operator^=(const uint64 &y) { return *this = *this ^ y; }
    ModInt operator~ () const { return *this ^ (MODULO - 2); }
    ModInt operator- () const { return make(set(MODULO - x)); }
    ModInt operator! () const { return getFact(uint32(*this)); }
    ModInt operator& () const { return getFinv(uint32(*this)); }
    ModInt operator++() { return *this = make(set(x + 1)); }
    ModInt operator--() { return *this = make(set(x + MODULO - 1)); }
    bool operator==(const ModInt &m) const { return x == m.x; }
    bool operator!=(const ModInt &m) const { return x != m.x; }
    bool operator< (const ModInt &m) const { return x <  m.x; }
    bool operator<=(const ModInt &m) const { return x <= m.x; }
    bool operator> (const ModInt &m) const { return x >  m.x; }
    bool operator>=(const ModInt &m) const { return x >= m.x; }
    explicit operator   bool() const { return x; }
    explicit operator uint64() const { return x; }
    ModInt operator^(uint64 y) const {
        uint64 t = x, u = 1;
        while (y) { if (y & 1) (u *= t) %= MODULO; (t *= t) %= MODULO; y >>= 1; }
        return make(u);
    }
    friend ostream &operator<<(ostream &os, const ModInt< MODULO > &m) { return os << m.x; }
    friend istream &operator>>(istream &is, ModInt< MODULO > &m) { uint64 y; is >> y; m = make(y); return is; }
    static vector< ModInt > fact, finv, invs;
    static void init(uint32 n) {
        uint32 m = fact.size();
        if (n < m) return;
        fact.resize(n + 1, 1);
        finv.resize(n + 1, 1);
        invs.resize(n + 1, 1);
        if (m == 0) m = 1;
        for (uint32 i = m; i <= n; ++i) fact[i] = fact[i - 1] * ModInt(i);
        finv[n] = ModInt(1) / fact[n];
        for (uint32 i = n; i >= m; --i) finv[i - 1] = finv[i] * make(i);
        for (uint32 i = m; i <= n; ++i) invs[i] = finv[i] * fact[i - 1];
    }
    static ModInt getFact(uint32 n) { init(n); return fact[n]; }
    static ModInt getFinv(uint32 n) { init(n); return finv[n]; }
    static ModInt getInvs(uint32 n) { init(n); return invs[n]; }
    static ModInt C(int64 n, int64 r) {
        if (r == 0) return make(1);
        if (r <  0) return make(0);
        if (n <  0) return make(r & 1 ? MODULO - 1 : 1) * C(-n + r - 1, r);
        if (n == 0 || n < r) return make(0);
        init(n);
        return fact[n] * finv[n - r] * finv[r];
    }
    //N<=10^5を超えるが,k<=10^5の時にO(k)で求める
    static ModInt CbyK(int64 n, int64 k){
        ModInt res=1;
        rep(i,k){
            res*=n-i;
            res/=i+1;
        }
        return res;
    }
    static ModInt P(int64 n, int64 r) {
        if (n < r || r < 0) return make(0);
        init(n);
        return fact[n] * finv[n - r];
    }
    static ModInt H(int64 n, int64 r) {
        if (n < 0 || r < 0) return make(0);
        if (!n && !r) return make(1);
        init(n + r - 1);
        return C(n + r - 1, r);
    }
    static ModInt montmort(uint32 n) {
        ModInt res;
        init(n);
        for (uint32 k = 2; k <= n; ++k) {
            if (k & 1) res -= finv[k];
            else res += finv[k];
        }
        return res *= fact[n];
    }
    static ModInt LagrangePolynomial(vector<ModInt> &y, ModInt t) {
        uint32 n = y.size() - 1;
        if (t.x <= n) return y[t.x];
        init(n + 1);
        ModInt res, num(1);
        for (uint32 i = 0; i <= n; ++i) num *= t - make(i);
        for (uint32 i = 0; i <= n; ++i) {
            ModInt tmp = y[i] * num / (t - make(i)) * finv[i] * finv[n - i];
            if ((n - i) & 1) res -= tmp;
            else res += tmp;
        }
        return res;
    }
};
template< int MODULO >
vector<ModInt< MODULO >> ModInt< MODULO >::fact = vector<ModInt< MODULO >>();
template< int MODULO >
vector<ModInt< MODULO >> ModInt< MODULO >::finv = vector<ModInt< MODULO >>();
template< int MODULO >
vector<ModInt< MODULO >> ModInt< MODULO >::invs = vector<ModInt< MODULO >>();
using modint = ModInt< MOD >;

/*
・ModInt
[備考] Mod演算のための構造体
[使用例]
modint M;           // 剰余系MOD(1e9+7)における演算ができる
ModInt<mod> N;      // 剰余系modにおける演算ができる
名前空間 modint::にいくつかの関数あり
*/
signed main() {
    ll n,a,b;cin>>n>>a>>b;
    vl h(n);
    ll lo = 1, hi = 1e9;
    while (lo <= hi) {
        ll t = 0;
        ll mid = (lo + hi) / 2;//二分
        rep(i,n) {
            ll tmp = h[i] - mid * b;
            if (tmp > 0) t += ceil((long double)tmp / (a - b));
        }
        if (t <= mid) hi = mid - 1;
        else lo = mid + 1;
    }
    cout<<hi+1<<endl;
}