Choroba I did it but again the same error-

Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, ,3:   M143<-M10<-Q = P,
Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, ,0:   M420<-M143<-M10<-Q = P,
Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, L,:   M407<-M143<-M10<-Q = P,
Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, 0:    M10<-Q = P,
Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, ,1:   M421<-M143<-M10<-Q = P,
Use of uninitialized value in print at final.pl line 71, <DATA> line 7
+.
, L,:   M406<-M143<-M10<-Q = P,
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LINE 71 being   print " = ", $path_string, ', ', $group{$path_string};