diff --git a/m1rc3/norruption/2/plot-cdf b/m1rc3/norruption/2/plot-cdf
index 832b9cb..8e2f394 100755
--- a/m1rc3/norruption/2/plot-cdf
+++ b/m1rc3/norruption/2/plot-cdf
@@ -1,4 +1,19 @@
 #!/usr/bin/perl
+
+sub usage
+{
+	print STDERR "usage: $0 [-i] [log_file]\n";
+	exit(1);
+}
+
+
+$with = "steps";
+if ($ARGV[0] eq "-i") {
+	shift @ARGV;
+	$with = "lines";
+}
+&usage if $ARGV[0] =~ /^-/;
+
 $n = 1;
 while (<>) {
 	next unless /^=== (\d+) ===/;
@@ -25,7 +40,7 @@ $cmd = "|gnuplot -e '".
     'set xlabel "Power cycles";'.
     'set ylabel "Cumulative probability";'.
     'set key bottom;'.
-    'plot "-" with steps title "Empirical distribution (N='.@f.')", '.
+    'plot "-" with '.$with.' title "Empirical distribution (N='.@f.')", '.
       '1-exp(-'.1/$f.'*x) with lines lt 3 '.
       'title "Exponential distribution ({/Symbol l}=1/'.$f.')"'.
     "'";