JumpingOnClouds.js

process.stdin.resume();
process.stdin.setEncoding('ascii');

var input_stdin = "";
var input_stdin_array = "";
var input_currentline = 0;

process.stdin.on('data', function (data) {
    input_stdin += data;
});

process.stdin.on('end', function () {
    input_stdin_array = input_stdin.split("\n");
    main();
});

function readLine() {
    return input_stdin_array[input_currentline++];
}

/////////////// ignore above this line ////////////////////

function main() {
    var n = parseInt(readLine());
    c = readLine().split(' ');
    c = c.map(Number);
    var counter = i = 0;
    while (i <= n) {
        if (!c[i + 2]) {
            i += 2;
        } else if (!c[i + 1]) {
            i += 1;
        }
        counter++;
    }
    console.log(counter - 1);
}