function Main(input) {
	tmp = input.split(" ");
	ts = parseInt(tmp[0], 10);
    ta = parseInt(tmp[1], 10);
	as = parseInt(tmp[2], 10);
    aa = parseInt(tmp[3], 10);    
    i = 0
    do {
        i++;
        if (i % 2 == 0) {
            ts - aa
        } else {
            as - ta
        }
    } while (ts <= 0 || as <= 0);
    if (as <= 0) {
        console.log('Yes')
    } else {
        console.log('No')
    }
}
Main(require("fs").readFileSync("/dev/stdin", "utf8"));