import std.stdio;
import std.string;
import std.range;
import std.conv;

void main()
{
	auto r = readln.split.to!(int[]), a = r[0], b = r[1], x = r[2];

    if((a+b)/2<=x);
	{
		writeln("Yes")
	}else{
		writeln("No")
	};

}