#include<bits/stdc++.h>
#define F first
#define S second
#define MP make_pair
#define pb push_back
#define endl '\n'

using namespace std;

typedef long long LL;
typedef pair< int, int > P;
typedef pair< LL, LL > LP;
typedef pair< int, P > iP;
typedef pair< P, P > PP;

static const int INF = INT_MAX;
static const LL LINF = LLONG_MAX;
static const int MIN = INT_MIN;
static const LL LMIN = LLONG_MIN;
static const int MOD = 1000000007;

int dx[] = {0, -1, 1, 0};
int dy[] = {-1, 0, 0, 1};

int main() {
    ios::sync_with_stdio(false);
    cin.tie(0);

    int a, b, c, d;
    cin >> a >> b >> c >> d;
    int cnt = 0;
    int all = c + 1;

    while( a > 0 && b >= c && all <= d ) {
        all += 1 + c;
        ++cnt;
        --a;
        b -= c;

    }

    cout << cnt << endl;
    return 0;
}