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

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

import std.stdio;

void main() {
    uint n, a = 0, b = 1, c = 0, ta, r;
    
    readf("%d", &n);
    
    while (--n) {
        ta = (b + c) % 1000000007;
        c = b; b = a; a = ta;
    }
    
    r = (a + b + c) % 1000000007UL;
    
    writeln(r);
}