"use strict";

function _slicedToArray(arr, i) { return _arrayWithHoles(arr) || _iterableToArrayLimit(arr, i) || _nonIterableRest(); }

function _nonIterableRest() { throw new TypeError("Invalid attempt to destructure non-iterable instance"); }

function _iterableToArrayLimit(arr, i) { var _arr = []; var _n = true; var _d = false; var _e = undefined; try { for (var _i = arr[Symbol.iterator](), _s; !(_n = (_s = _i.next()).done); _n = true) { _arr.push(_s.value); if (i && _arr.length === i) break; } } catch (err) { _d = true; _e = err; } finally { try { if (!_n && _i["return"] != null) _i["return"](); } finally { if (_d) throw _e; } } return _arr; }

function _arrayWithHoles(arr) { if (Array.isArray(arr)) return arr; }

function main(input) {
  var lines = input.split('\n');

  var _splitNum = splitNum(lines.shift()),
      _splitNum2 = _slicedToArray(_splitNum, 2),
      N = _splitNum2[0],
      K = _splitNum2[1];

  var hs = lines.slice(0, N).map(function (l) {
    return parseInt(l);
  });
  hs.sort(function (a, b) {
    return a - b;
  });
  var gdiff = Infinity;

  for (var i = 0; i <= N - K; i++) {
    var min = Infinity,
        max = -Infinity;

    for (var j = i; j < i + K; j++) {
      if (min > hs[j]) {
        min = hs[j];
      }

      if (max < hs[j]) {
        max = hs[j];
      }
    }

    var diff = max - min;

    if (gdiff > diff) {
      gdiff = diff;
    }
  }

  console.log(gdiff);
}

main(require('fs').readFileSync('/dev/stdin', 'utf8'));

function splitNum(line) {
  return line.split(/\s+/).map(function (n) {
    return parseInt(n);
  });
}
