The energy of a droplet of plus spins in a minus background is proportional to the perimeter of the droplet L, where plus spins and minus spins neighbor each other. For a droplet with perimeter "L", the area is somewhere between ("L" − 2)/2 (the straight line) and ("L"/4)2 (the square box). The probability cost for introducing a droplet has the factor "e"−β"L", but this contributes to the partition function multiplied by the total number of droplets with perimeter "L", which is less than the total number of paths of length "L":