#include <bits/stdc++.h>

using namespace std;

vector<string> split_string(string);

// Complete the kangaroo function below.
string kangaroo(int x1, int v1, int x2, int v2) {

    int flag = 1;
    map<int,int> m;
    m[x1] = v1;
    m[x2]  = v2;
    map<int,int>::iterator it;
    it = m.begin();
    it++;

    int first = m.begin()->first;
    int second = it->first;
    int min = second-first;
    while(flag ==1)
    {
        map<int,int>::iterator it2;
        it2 = m.begin();
        it++;
        first +=m.begin()->second;
        second +=it2->second;
        if(first==second)
        {
            cout<<"hii";
           return "YES";
           flag = 0;
        }
        cout<<min<<endl;
        min = second -first;
        if(min<0)
        {
            cout<<"bye";
           return "NO";
           flag = 0;
        }

    }
    return "dummy";

}

int main()
{
    ofstream fout(getenv("OUTPUT_PATH"));

    string x1V1X2V2_temp;
    getline(cin, x1V1X2V2_temp);

    vector<string> x1V1X2V2 = split_string(x1V1X2V2_temp);

    int x1 = stoi(x1V1X2V2[0]);

    int v1 = stoi(x1V1X2V2[1]);

    int x2 = stoi(x1V1X2V2[2]);

    int v2 = stoi(x1V1X2V2[3]);

    string result = kangaroo(x1, v1, x2, v2);

    fout << result << "\n";

    fout.close();

    return 0;
}

vector<string> split_string(string input_string) {
    string::iterator new_end = unique(input_string.begin(), input_string.end(), [] (const char &x, const char &y) {
        return x == y and x == ' ';
    });

    input_string.erase(new_end, input_string.end());

    while (input_string[input_string.length() - 1] == ' ') {
        input_string.pop_back();
    }

    vector<string> splits;
    char delimiter = ' ';

    size_t i = 0;
    size_t pos = input_string.find(delimiter);

    while (pos != string::npos) {
        splits.push_back(input_string.substr(i, pos - i));

        i = pos + 1;
        pos = input_string.find(delimiter, i);
    }

    splits.push_back(input_string.substr(i, min(pos, input_string.length()) - i + 1));

    return splits;
}