import std;

bool calc(long l, long r, long m, long k) {
    auto lo = k * l;
    auto hi = k * r;
    // 区間 [lo, hi] に m の倍数があるか


    // return lo <= hi / m * m;

    return (lo + m - 1) / m * m <= hi;
}

void main() {
    long l, r, m, k; scan(l, r, m, k);
    writeln(calc(l, r, m, k) ? "Yes" : "No");
}

void scan(T...)(ref T a) {
    string[] ss = readln.split;
    foreach (i, t; T) a[i] = ss[i].to!t;
}
T read(T=string)() { return readln.chomp.to!T; }
T[] reads(T)() { return readln.split.to!(T[]); }
alias readints = reads!int;