Convert CGG Velocity to Omega Format using Perl

Perl Code:
#!/usr/bin/perl
my $i=1;
while (<>) {
chomp;
@s = split ;  #split data into lines

#################################
if (/VSTKT/) #grep lines contain VSTKT
{
push @inlin, @s[0];   #push into inline
push @xline, @s[1];
push @datum, @s[2];
push @cmp, @s[3];
}

####################begin push with restriction
if ($_!~/VSTKT/ && $_!~/CGG/ ) #select lines doesn't contain VSTKT and CGG
{
$numel=@s;  #count no of elements in each line
for ($j=0; $j<=$numel-1; $j++)
{
push @sa,$s[$j]; #push data into array
}
}
####################end push
}
$numel2=@sa;
for ($j=0; $j<=($numel2-1)/2; $j++)
{
push @time,$sa[$j*2];   #select odd lines
push @vels,$sa[$j*2+1]; #select even lines
}

$numel3=@time;
for ($j=0; $j<=$numel3; $j++)
{
$dt[$j]=$time[$j+1]-$time[$j];  #calculate time difference
push @dtx, $dt[$j]; #push
}

my (@index) = grep $dtx[$_] < 0, 0 .. $#dtx;  #locate negative time difference i.e. new cmp

$numel4=@index;
for ($j=0; $j<=$numel4-2; $j++)
{
$idx[$j]=$index[$j+1]-$index[$j];  #calculate no of analysis points
push @idx2,$idx[$j];
}
push @idx3, $index[0]+1, @idx2;  #calculate no of analysis points

$numel5=@idx3;

for $m (0..$numel5-1)  #no cmp
{
@time1=@time[$index[$m]-($idx3[$m]-1)..$index[$m]];
@vels1=@vels[$index[$m]-($idx3[$m]-1)..$index[$m]];

printf "%s", "SPNT";
printf  "%11d",$cmp[$m];
printf  "%25d",$xline[$m];
printf  "%20d",$inlin[$m];


print "\n";
for $k (0..$idx3[$m]/5)
{
printf "%s", "VELF";
for $i (1..5)
{
if ($vels1[$i+$k*5-1] > 0)   #exist vel
{

if ($i == 1 && $k==0) #beginning of analysis points
{
printf  "%11d",$cmp[$m];
printf  "%5d",$datum[$m];
printf  "%5d",$time1[$i+$k*5-1];
}

elsif ($i == 1 && $k==1 )  #row no 2 in omega format of each cmp
{
printf  "%21d",$time1[$i+$k*5-1];}

elsif ($i == 1 ) #rest of analysis points
{
printf  "%21d",$time1[$i+$k*5-1];
}

else
{
printf  "%5d",$time1[$i+$k*5-1];
}
printf  "%5d",$vels1[$i+$k*5-1];
}
}
print "\n";
}
@time1=();
@vels1=();
}