var first = 1;
var last = 5;
var current = 1;
           
function slideshow() {
    // Hide current picture
    object = document.getElementById('slide' + current);
    object.style.display = 'none';

    // Show next picture, if last, loop back to front
    if (current == last) { current = 1; }
    else { current++ }
    object = document.getElementById('slide' + current);
    object.style.display = 'block';
    setTimeout(slideshow, 10000);
}