a, b, c, d = map(int, input().split())
ans = 0
while True:
    if b - c >= 0:
        b -= c
        if a > 0:
            a -= 1
            if d - (c+1) >= 0:
                d -= c+1
                ans += 1
            else:
                break
        else:
            break
    else:
        break
print(ans)