// yukicoder My Practice
// author: Leonardone @ NEETSDKASU

process.stdin.resume();
process.stdin.setEncoding('utf8');

// 解説読後
// http://yukicoder.me/problems/882/editorial

process.stdin.on('data', function(chunk) {
    var n = parseInt(chunk.toString());
    
    var a = 0, b = 1, c = 0, ta;
    
    while (--n > 0) {
        ta = (b + c) % 1000000007;
        c = b;
        b = a;
        a = ta;
    }
    
    console.log((a + b + c) % 1000000007);
});