ll n,m,a[1d3][1d3],b,c,d;
{
	rd(n,m,a(n)(m));
	rep(i,n){
		b=0;
		rep(j,m)b+=a[i][j];
		c>?=d+b;
		d>?=c-b;
	}
	wt(max(c,d));
}