unittest
{
	assert( [ "10 9 10 10" ].parse.expand.solve == "No" );
	assert( [ "46 4 40 5" ].parse.expand.solve == "Yes" );
}



import std.conv;
import std.range;
import std.stdio;
import std.typecons;

void main()
{
	stdin.byLineCopy.parse.expand.solve.writeln;
}

auto parse( Range )( Range input )
if( isInputRange!Range && is( ElementType!Range == string ) )
{
	auto abcd = input.front.split.to!( long[] );
	return tuple( abcd[ 0 ], abcd[ 1 ], abcd[ 2 ], abcd[ 3 ] );
}

auto solve( long a, long b, long c, long d )
{
	while( true )
	{
		c -= b;
		if( c <= 0 ) return "Yes";
		a -= d;
		if( a <= 0 ) return "No";
	}
}
