// JavaScript Document

var step = 1;

function change_source(){

if(step == 1){
	
	var imgsrc = "images/seminar_08/images/start.png";
	
	document.getElementById('semi_img').src = imgsrc;
	
	document.getElementById('semi_img').style.border = "none";
	
	document.getElementById('img_nr').innerHTML = step;	
	
	return;
		
}
else{
	var imgsrc = "images/seminar_08/images/" + step + ".jpg";
	
	document.getElementById('semi_img').src = imgsrc;
	
	document.getElementById('semi_img').style.border = "1px solid #232323";
	
	document.getElementById('img_nr').innerHTML = step;	
	
	return;
}
}


function step_forw(img){
	
	if (step == 78){
	
		step = 1;
		
		change_source();
	
	}
	
	else {

	step = step + 1;
	
	change_source();
	
	}

}

function step_back(img){
	
	if (step == 1){
		
		step = 78;
		
		change_source();
	
	}
	
	else {
		
		step = step - 1;
		
		change_source()
	}

}

function show_step(){
	
	document.write(step);	
}