function Main(input) {
    input = input.split('\n')
    input.shift();
    var sheet = {};
    input.forEach(function(e) {
        if (sheet[e]) {
            sheet[e] = 0
        } else {
            sheet[e] = 1
        }
    });
    var r = 0;
    for (var key in sheet) {
        if (sheet[key])
            r++
    }
    console.log(r)