Selecting First Incidence from Longitudinal Data

I have a longitudinal competing risk data of the form:

ID    COMPL  SEX   HEREDITY
1     0       1      2
1     0       1      2
1     3       1      2
2     0       0      1
2     1       0      1
2     2       0      1
2     2       0      1
3     0       0      1
3     0       0      1
3     0       0      1
3     0       0      1
3     2       0      1
4     0       1      2
4     0       1      2.

Where, COMPL= health complication of diabetic patients which has value
labels   as  0= no complication,1=coronary heart disease, 2=retinopathy, 3=
nephropathy.


I want to select only the first complication that occurred to each patient.
What R function can I use?

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