unittest
{
	assert( [ "100 17" ].parse.expand.solve == 83 );
	assert( [ "48 58" ].parse.expand.solve == 0 );
	assert( [ "1000000000 1000000000" ].parse.expand.solve == 0 );
}



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

void main()
{
	stdin.byLineCopy.parse.expand.solve.writeln;
}

auto parse( Range )( Range input )
if( isInputRange!Range && is( ElementType!Range == string ) )
{
	auto xt = input.front.split.to!( long[] );
	return tuple( xt[ 0 ], xt[ 1 ] );
}

auto solve( long x, long t )
{
	auto r = x - t;
	return ( 0 <= r ) ? r : 0;
}
