import strutils, sequtils, algorithm

var
  N, X = stdin.readLine.split.map parseInt
  best = int.high

X.sort(cmp)

for i in 1 .. X.high:
  let d = X[i] - X[i - 1]
  if d != 0: best = min(best, d)

[best, 0][int(best == int.high)].echo