Updating pie chart via form data

HTML

<script type="text/javascript" src="http://www.amcharts.com/lib/3/amcharts.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/pie.js"></script>
<script type="text/javascript" src="http://www.amcharts.com/lib/3/themes/none.js"></script>
<div id="chartdiv"></div>
<input type="text" id="title-0" value="" placeholder="Slice #1 title" />
<input type="text" id="value-0" value="" placeholder="Slice #1 value" /><br />
<input type="text" id="title-1" value="" placeholder="Slice #2 title" />
<input type="text" id="value-1" value="" placeholder="Slice #2 value" /><br />
<input type="text" id="title-2" value="" placeholder="Slice #3 title" />
<input type="text" id="value-2" value="" placeholder="Slice #3 value" /><br />
<input type="text" id="title-3" value="" placeholder="Slice #4 title" />
<input type="text" id="value-3" value="" placeholder="Slice #4 value" /><br />
<input type="text" id="title-4" value="" placeholder="Slice #5 title" />
<input type="text" id="value-4" value="" placeholder="Slice #5 value" /><br />
<input type="button" value="Update chart" onclick="updateChart();" />

CSS

#chartdiv {
	width		: 100%;
	height		: 500px;
	font-size	: 11px;
}

JavaScript

var chart = AmCharts.makeChart("chartdiv", {
    "type": "pie",
	"theme": "none",
    "dataProvider": [
{
        "country": "Lithuania",
        "litres":500.10
    },
{
        "country": "Czech Republic",
        "litres": 301.9
    }, {
        "country": "Ireland",
        "litres": 201.1
    }, {
        "country": "Germany",
        "litres": 165.8
    }, {
        "country": "Australia",
        "litres": 139.9
    }, {
        "country": "Austria",
        "litres": 128.3
    }, {
        "country": "UK",
        "litres": 99
    }, {
        "country": "Belgium",
        "litres": 60
    }, {
        "country": "The Netherlands",
        "litres": 50
    }],
    "valueField": "litres",
    "titleField": "country",
	"exportConfig":{	
      menuItems: [{
      icon: '/lib/3/images/export.png',
      format: 'png'	  
      }]  
	}
});

function updateChart () {
    chart.dataProvider = [];
    for (var i = 0; i <= 4; i++) {
        if (Number(document.getElementById('value-'+i).value)) {
            chart.dataProvider.push({
                "country": document.getElementById('title-'+i).value,
                "litres": Number(document.getElementById('value-'+i).value)
            })
        }
    }
    console.log(chart.dataProvider);
    chart.validateData();
}