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class Solution {
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  public int removeCoveredIntervals(int[][] intervals) {
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    if (intervals == null || intervals.length == 0) return 0;
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    Arrays.sort(intervals, (i1, i2) -> (i1[0] == i2[0] ? i2[1] - i1[1] : i1[0] - i2[0]));
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    int c = intervals[0][0], d = intervals[0][1];
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    int ans = intervals.length;
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    for (int i = 1; i < intervals.length; i++) {
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      int a = intervals[i][0], b = intervals[i][1];
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      if (c <= a && b <= d) ans--;
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      else {
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        c = a;
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        d = b;
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      }
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    }
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    return ans;
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  }
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}