$elem[0] = "SHAPES GREEN1;SIZE 240 500 340 930;SIZE 350 500 240 590;SIZE 295 390 015 490;SIZE 350 210 760 300;";

$elem[1] = "SHAPES GREEN2;SIZE 450 310 680 690;SIZE 450 110 680 490;SIZE 215 800 560 900;";

##</code><code>##

my @matches = ( $inp_line =~ /(SHAPES \w+;(?:SIZE[ \d+])+;)/g );

##</code><code>##

my @matches;
for ( @inp_lines ) {
    push @matches, ( /(SHAPES \w+;(?:SIZE[ \d+])+;)/g );
}

##</code><code>##

s/(?<=\d;)(?=SHAPES )/\n/;  # using "look-behind" and "look-ahead 

# now just split on "\n"...