package Practice;

import java.io.BufferedReader;

import java.io.InputStreamReader;

import java.util.StringTokenizer;

public class B24313 { //알고리즘 수업 - 점근적 표기 1

public static void main(String[] args) throws Exception {

// TODO Auto-generated method stub

BufferedReader br = new BufferedReader(new InputStreamReader(System.in));

StringTokenizer st = new StringTokenizer(br.readLine());

int A1 = Integer.parseInt(st.nextToken()), A2 = Integer.parseInt(st.nextToken()); //정수

int C = Integer.parseInt(br.readLine()), N0 = Integer.parseInt(br.readLine()); //양의 정수

int n = C - A1; //n

if(n < 0) {

System.out.println(0);

return ;

}

if(n == 0) {

if(A2 <= 0) System.out.println(1);

else System.out.println(0);

return ;

}

if(A2 % n != 0) A2 = A2 / n + 1;

else A2 = A2 / n;

if(N0 >= A2) System.out.println(1);

else System.out.println(0);

}

}