DB<49> @c = ([12,15], [12,17], [13,14], [14,19])

  DB<50> x @c
0  ARRAY(0x20498b98)
   0  12
   1  15
1  ARRAY(0x20499588)
   0  12
   1  17
2  ARRAY(0x2049c428)
   0  13
   1  14
3  ARRAY(0x2049c488)
   0  14
   1  19
  DB<51> $e = 17

  DB<52> $_->[2]++ foreach grep {$e <= $_->[1]} grep {$e >= $_->[0]} @c

  DB<53> x @c
0  ARRAY(0x20498b98)
   0  12
   1  15
1  ARRAY(0x20499588)
   0  12
   1  17
   2  1
2  ARRAY(0x2049c428)
   0  13
   1  14
3  ARRAY(0x2049c488)
   0  14
   1  19
   2  1
  DB<54> $e = 13;

  DB<55> $_->[2]++ foreach grep {$e <= $_->[1]} grep {$e >= $_->[0]} @c

  DB<56> x @c
0  ARRAY(0x20498b98)
   0  12
   1  15
   2  1
1  ARRAY(0x20499588)
   0  12
   1  17
   2  2
2  ARRAY(0x2049c428)
   0  13
   1  14
   2  1
3  ARRAY(0x2049c488)
   0  14
   1  19
   2  1
  DB<57>