import std.conv, std.stdio, std.string; import std.algorithm, std.array, std.bigint, std.container, std.math, std.numeric, std.range, std.regex, std.typecons; import core.bitop; class EOFException : Throwable { this() { super("EOF"); } } string[] tokens; string readToken() { for (; tokens.empty; ) { if (stdin.eof) { throw new EOFException; } tokens = readln.split; } auto token = tokens.front; tokens.popFront; return token; } int readInt() { return readToken.to!int; } long readLong() { return readToken.to!long; } real readReal() { return readToken.to!real; } bool chmin(T)(ref T t, in T f) { if (t > f) { t = f; return true; } else { return false; } } bool chmax(T)(ref T t, in T f) { if (t < f) { t = f; return true; } else { return false; } } int binarySearch(T)(in T[] as, in bool delegate(T) test) { int low = -1, upp = cast(int)(as.length); for (; low + 1 < upp; ) { int mid = (low + upp) >> 1; (test(as[mid]) ? low : upp) = mid; } return upp; } int lowerBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a < val)); } int upperBound(T)(in T[] as, in T val) { return as.binarySearch((T a) => (a <= val)); } /* X^2 - 2 X - 2 a[n] = (1 + sqrt(3))^n + (1 - sqrt(3))^n a[0] = 2, a[1] = 2, a[n] = 2 a[n - 1] + 2 a[n - 2] -1 < 1 - sqrt(3) < 0 */ enum MO = 1000L; alias P = Tuple!(long, long); P mul(in P a, in P b) { P c = P(a[0] * b[0], a[0] * b[1] + a[1] * b[0]); long c2 = a[1] * b[1]; c[0] += 2 * c2; c[1] += 2 * c2; c[0] %= MO; c[1] %= MO; return c; } void main() { try { for (; ; ) { const N = readLong(); long ans; if (N == 0) { ans = 1; } else { P a = P(0, 1), b = P(1, 0); for (long n = N; n; n >>= 1) { if (n & 1) { b = mul(b, a); } a = mul(a, a); } ans = (2 * b[0] + 2 * b[1]) % MO; if (N % 2 == 0) { ans = (ans - 1 + MO) % MO; } } writeln(ans); } } catch (EOFException e) { } }