#!/usr/bin/perl -w

use 5.030;

my $opt;

decision:
print "Do you want small number of firms index of concentration [H] or a [B]ig number of firms index: ";
chomp (my $r = <STDIN>);
if ($r =~ /[Bb]/) { 
    $opt = 2;
    big();
}elsif ($r =~ /[Hh]/) { 
    $opt = 1 ; 
    Herfindahl();
}else{
    goto decision;
}

say "Remember that all oligopoly carry inside the seed of its destruction.";

exit 1;

sub big {
n:    
    print "Enter the number of firms in the sector: ";
    chomp (my $n = <STDIN>);
    goto n if (0+$n ne $n);
V:    
    print "Enter the variance of market quota of a normal firm: ";
    chomp (my $V = <STDIN>);
    goto V if (0+$V ne $V);
    
    my $result = 1/$n + $n * $V;
    say "The aproximate H index is $result";
    if ($result >= 1800){
	say "Begin to bother!";
    }else{
	print "Begin to bother if variance goes up ", (1800-1/$n)/$n, "\n";
    }
}


sub Herfindahl {
    say "Enter the quota of the market in % number of the big firms, separated by spaces: ";
    chomp ($r = <STDIN>);
    my @q = split /\s+/, $r;
    my $sum;
    for my $i (@q){
	$sum += $i*$i if (0+$i eq $i);
    }
    say "The minimun HH index is $sum";
    say "Begin to bother!" if ($sum >= 1800);
}

__END__

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