#include <iostream>
using namespace std;
#define NUM 1000000007
int main(){
    int n;
    cin>>n;
    long long temp[3];
    temp[0] = 0;temp[1]=1;temp[2]=2;
    for(int i=3;i<=n;i++){
        temp[0] = temp[1];
        temp[1] = temp[2];
        temp[2] = ((temp[0]+temp[1])%NUM)%NUM;
    }
    cout<<temp[2]<<endl;
    return 0;
}