procedure tgroup (file_name, n, x, y)

string file_name {prompt="Input file containing a stream of words"}
real n {prompt="Number of lines over which group pattern is repeated"}
real x {prompt="First line (of group) to include"}
real y {prompt="Last line (of group) to include"}
struct *flist

begin

	string nthWORD
	struct currentWORD
	real j			# counter
	real Y
	real Yint

	flist = file_name

	j = 0.

	while (fscan (flist, currentWORD) != EOF) {

		j=j+1.
		if (j > n) {
			j = 1.
		}


		if ((j >= x) && (j <= y)) {
			print (currentWORD)
		}



	}

end