unittest
{
	assert( [ "4 5" ].parse.expand.solve == "unsafe" );
	assert( [ "100 2" ].parse.expand.solve == "safe" );
	assert( [ "10 10" ].parse.expand.solve == "unsafe" );
}



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 sw = input.front.split.to!( long[] );
	return tuple( sw[ 0 ], sw[ 1 ] );
}

auto solve( long s, long w )
{
	return ( s <= w ) ? "unsafe" : "safe";
}
