#include<bits/stdc++.h>
using namespace std;
int main()
{
	int x,y,a,b;
	cin>>x>>y;
	if(x>=-1&&x<=1&&y>=-1&&y<=1) {
	cout<<"yes";
	} else cout<<"no";
	 
	return 0;
}

#include<bits/stdc++.h>
using namespace std;
int main()
{
	int x,y,a,b;
	cin>>x>>y;
	if(x>=-1&&x<=1&&y>=-1&&y<=1) {
	cout<<"yes";
	} else cout<<"no";
	 
	return 0;
}

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