unittest
{
	assert( [ "3 2 6" ].parse.expand.solve == 1 );
	assert( [ "3 1 3" ].parse.expand.solve == 0 );
	assert( [ "5 10 1" ].parse.expand.solve == 4 );
}



import std.conv;
import std.math;
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 wab = input.front.split.to!( long[] );
	return tuple( wab[ 0 ], wab[ 1 ], wab[ 2 ] );
}

auto solve( long w, long a, long b )
{
	auto d = ( a - b ).abs;
	if( d <= w ) return 0;
	else         return d - w;
}
