function c_update(){
	composer=document.getElementById('composer');
	new_composer=document.getElementById('new_composer');
	new_c=document.getElementById('new_c');
	if(composer.value<0)
		new_c.style.display='block';
	else{
		new_composer.value='';
		new_c.style.display='none';
	}
}

function r_update(){
	performer=document.getElementById('performer');
	new_performer=document.getElementById('new_performer');
	new_r=document.getElementById('new_r');
	if(performer.value<0)
		new_r.style.display='block';
	else{
		new_performer.value='';
		new_r.style.display='none';
	}
}

function p_update(){
	period=document.getElementById('period');
	new_period=document.getElementById('new_period');
	new_p=document.getElementById('new_p');
	if(period.value<0)
		new_p.style.display='block';
	else{
		new_period.value='';
		new_p.style.display='none';
	}
}

function f_update(){
	form=document.getElementById('form');
	new_form=document.getElementById('new_form');
	new_f=document.getElementById('new_f');
	if(form.value<0)
		new_f.style.display='block';
	else{
		new_form.value='';
		new_f.style.display='none';
	}
}

function i_update(){
	instrument=document.getElementById('instrument');
	new_instrument=document.getElementById('new_instrument');
	new_i=document.getElementById('new_i');
	if(instrument.value<0)
		new_i.style.display='block';
	else{
		new_instrument.value='';
		new_i.style.display='none';
	}
}