#include <iostream>
#include <cmath>
#include <vector>
using namespace std;

typedef vector<int> vec;
typedef vector<vec> mat;
typedef long long ll;

mat mul(mat &A, mat&B) {
    mat C(A.size(), vec(B[0].size()));
    for(int i = 0; i < (int)A.size(); i++){
        for(int j = 0; j < (int)B[0].size(); j++){
            for(int k = 0; k < (int)B.size(); k++){
                C[i][j] = (C[i][j] + A[i][k] * B[k][j]) % 1000;
            }
        }
    }
    return C;
}

mat pow(mat A, ll n) {
    mat B(A.size(), vec(A.size()));
    for(int i = 0; i < (int)A.size(); i++){
        B[i][i] = 1;
    }
    while(n > 0){
        if(n & 1) B = mul(B, A);
        A = mul(A, A);
        n >>= 1;
    }
    return B;
}

int n;

int solve() {
    mat A(2, vec(2, 0));
    A[0][0] = 1; A[0][1] = 3;
    A[1][0] = 1; A[1][1] = 1;
    A = pow(A, n);
    int ans = A[0][0]*2 - (n%2 == 0 ? 1 : 0);
    ans += 2000;
    return ans % 1000;
}

int main(){
    while(cin >> n) cout << solve() << endl;
}