function zamiana() {
var i;
if (screen.height <= 600)
for(i=0;i<document.images.length;i++)
document.images[i].src = document.images[i].src.replace('srednie','male');
else if (screen.height > 600 && screen.height <= 800)
for(i=0;i<document.images.length;i++)
document.images[i].src = document.images[i].src.replace('srednie','srednie');
else 
for(i=0;i<document.images.length;i++)
document.images[i].src = document.images[i].src.replace('srednie','duze');
}