/home/stepan7/sandbox/main.php:40:
array(2) {
  [0] =>
  int(1)
  [1] =>
  int(37)
}
/home/stepan7/sandbox/main.php:15:
int(1)
/home/stepan7/sandbox/main.php:42:
array(40) {
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    NULL
    [6] =>
    NULL
    [8] =>
    NULL
    [12] =>
    NULL
    [13] =>
    NULL
    [17] =>
    NULL
    [19] =>
    NULL
    [22] =>
    NULL
    [27] =>
    NULL
    [30] =>
    NULL
    [31] =>
    NULL
    [32] =>
    NULL
    [33] =>
    NULL
    [34] =>
    NULL
    [35] =>
    NULL
    [36] =>
    NULL
    [38] =>
    NULL
    [39] =>
    NULL
    [40] =>
    NULL
  }
  [2] =>
  array(3) {
    [3] =>
    NULL
    [4] =>
    NULL
    [5] =>
    NULL
  }
  [3] =>
  array(0) {
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  [4] =>
  array(0) {
  }
  [5] =>
  array(0) {
  }
  [6] =>
  array(1) {
    [7] =>
    NULL
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  [7] =>
  array(0) {
  }
  [8] =>
  array(3) {
    [9] =>
    NULL
    [10] =>
    NULL
    [11] =>
    NULL
  }
  [9] =>
  array(0) {
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  [10] =>
  array(0) {
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  [11] =>
  array(0) {
  }
  [12] =>
  array(0) {
  }
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  array(3) {
    [14] =>
    NULL
    [15] =>
    NULL
    [16] =>
    NULL
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  array(0) {
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  [15] =>
  array(0) {
  }
  [16] =>
  array(0) {
  }
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  array(1) {
    [18] =>
    NULL
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  array(0) {
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    NULL
    [21] =>
    NULL
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  array(0) {
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  [21] =>
  array(0) {
  }
  [22] =>
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    [24] =>
    NULL
    [25] =>
    NULL
    [26] =>
    NULL
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  [23] =>
  array(0) {
  }
  [24] =>
  array(0) {
  }
  [25] =>
  array(0) {
  }
  [26] =>
  array(0) {
  }
  [27] =>
  array(2) {
    [28] =>
    NULL
    [29] =>
    NULL
  }
  [28] =>
  array(0) {
  }
  [29] =>
  array(0) {
  }
  [30] =>
  array(0) {
  }
  [31] =>
  array(0) {
  }
  [32] =>
  array(0) {
  }
  [33] =>
  array(0) {
  }
  [34] =>
  array(0) {
  }
  [35] =>
  array(0) {
  }
  [36] =>
  array(0) {
  }
  [37] =>
  array(0) {
  }
  [38] =>
  array(0) {
  }
  [39] =>
  array(0) {
  }
  [40] =>
  array(0) {
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}
PHP ArgumentCountError:  Too few arguments to function dfs(), 2 passed in /home/stepan7/sandbox/main.php on line 74 and exactly 3 expected in /home/stepan7/sandbox/main.php on line 62
PHP Stack trace:
PHP   1. {main}() /home/stepan7/sandbox/main.php:0
PHP   2. dfs() /home/stepan7/sandbox/main.php:74
PHP Fatal error:  Uncaught ArgumentCountError: Too few arguments to function dfs(), 2 passed in /home/stepan7/sandbox/main.php on line 74 and exactly 3 expected in /home/stepan7/sandbox/main.php:62
Stack trace:
#0 /home/stepan7/sandbox/main.php(74): dfs()
#1 {main}
  thrown in /home/stepan7/sandbox/main.php on line 62