Finding all consecutive numbers of different lengths within a vector

I am trying to create a new vector based on the example vector below. This new vector needs to contain only the first value of each group of consecutive numbers. For example, from the vector below, I would want a new vector X that contains [25 55 80 100 155]. Thanks for the help in advance!

A = [25 26 27 28 55 56 80 81 82 100 101 102 103 104 105 155 156]

[KSSV]

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Answer 1

[Stephen23]

>> A = [25,26,27,28,55,56,80,81,82,100,101,102,103,104,105,155,156];
>> X = A([true,diff(A)~=1])
X =
    25    55    80   100   155

[BobbyRoberts]

Perfect! Thanks!