unittest
{
	assert( [ "oxoxoxoxoxoxox" ].parse.expand.solve == "YES" );
	assert( [ "xxxxxxxx" ].parse.expand.solve == "NO" );
}



import std.algorithm;
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 s = input.front;
	return tuple( s );
}

auto solve( string s )
{
	return ( 8 <= 15 - s.count( 'x' ) ) ? "YES" : "NO";
}
