

void main(){
	
	auto ABCD = readLine!long();
	
	foreach( i ; 0..102 ){
		ABCD[2] -= ABCD[1];
		if( ABCD[2] <= 0 ){	writeln("Yes");return;	}
		ABCD[0] -= ABCD[3];
		if ( ABCD[0] <= 0 ){	writeln("No");return;	}
	}
	
	
}


import std.stdio, std.string, std.conv;
import std.math, std.algorithm, std.array;
import std.regex;

T[] readLine( T = size_t )( string sp = " " ){
	T[] ol;
	foreach( string elm ; readln().chomp().split(sp) ){
		ol ~= elm.to!T();
	}
	return ol;
}