my %presence;
while(<INPUT>) {
    my($name, $from, $to) = /^(\w+):\s+(\d+)\s+.*?\s+(\d+)$/ or next;
    push @{$presence{$name}}, { from => $from, to => $to };
    # or, with arrays:
    # push @{$presence{$name}}, [ $from, $to ];
}