// yukicoder My Practice
// author: Leonardone @ NEETSDKASU
#include <stdio.h>

typedef unsigned long ul;

const ul MD = 1000000007UL;

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


int main(void) {
    
    register ul a, b = 1UL, c, ta, n;
    int k;
    
    scanf("%d", &k);
    n = k;
    
    while (--n) {
        ta = (b + c) % MD;
        c = b;
        b = a;
        a = ta;
    }

    
    printf("%lu\n", (a + b + c) % MD);
    
    return 0;
}