#include <bits/stdc++.h>

#define FOR(i,a,b) for(int i= (a); i<((int)b); ++i)
#define RFOR(i,a) for(int i=(a); i >= 0; --i)
#define FOE(i,a) for(auto i : a)
#define ALL(c) (c).begin(), (c).end()
#define RALL(c) (c).rbegin(), (c).rend()
#define DUMP(x)  cerr << #x << " = " << (x) << endl;
#define SUM(x) std::accumulate(ALL(x), 0LL)
#define MIN(v) *std::min_element(v.begin(), v.end())
#define MAX(v) *std::max_element(v.begin(), v.end())
#define EXIST(v,x) (std::find(v.begin(), v.end(), x) != v.end())
#define BIT(n) (1LL<<(n))
#define UNIQUE(v) v.erase(unique(v.begin(), v.end()), v.end());

typedef long long LL;
template<typename T> using V = std::vector<T>;
template<typename T> using VV = std::vector<std::vector<T>>;
template<typename T> using VVV = std::vector<std::vector<std::vector<T>>>;
template<typename T> using VVVV = std::vector<std::vector<std::vector<std::vector<T>>>>;

template<class T> inline T ceil(T a, T b) { return (a + b - 1) / b; }
template<class T> inline void print(T x) { std::cout << x << std::endl; }
template<class T> inline void print_vec(const std::vector<T> &v) { for (int i = 0; i < v.size(); ++i) {  if (i != 0) {std::cout << " ";} std::cout << v[i];} std::cout << "\n"; }
template<class T> inline bool inside(T y, T x, T H, T W) {return 0 <= y and y < H and 0 <= x and x < W; }
template<class T> inline double euclidean_distance(T y1, T x1, T y2, T x2) { return sqrt((x1 - x2) * (x1 - x2) + (y1 - y2) * (y1 - y2)); }
template<class T> inline double manhattan_distance(T y1, T x1, T y2, T x2) { return abs(x1 - x2) + abs(y1 - y2); }

const int INF = 1L << 30;
const double EPS = 1e-9;
const std::string YES = "YES", Yes = "Yes", NO = "NO", No = "No";
const std::vector<int> dy4 = { 0, 1, 0, -1 }, dx4 = { 1, 0, -1, 0 };    // 4近傍（右, 下, 左, 上）
const std::vector<int> dy8 = { 0, -1, 0, 1, 1, -1, -1, 1 }, dx8 = { 1, 0, -1, 0, 1, 1, -1, -1 };

using namespace std;



void solve(int N, V<pair<int, int>> v) {

    VV<int> dp(N + 1, V<int>(4, INF));
    dp[0][0] = 0;

    FOR(i, 0, N) {
        int p = v[i].first;
        int t = v[i].second;

        int pre_p = 0;
        int pre_t = 0;
        if (i != 0) {
            pre_p = v[i - 1].first;
            pre_t = v[i - 1].second;
        }

        int dist = abs(pre_p - p);

        bool ok = false;
        FOR(b, 0, 4) {
            if (dp[i][b] == INF) {
                continue;
            }

            // 直接とりにいく
            if (b + 1 <= 3 and pre_t + dist * (b + 1) <= t) {
                dp[i + 1][b + 1] = min(dp[i + 1][b + 1], dp[i][b] + dist);
                ok = true;
            }

            // 家に帰ってからとりにいく
            if (pre_t + pre_p * (b + 1) + p <= t) {
                dp[i + 1][1] = min(dp[i + 1][1], dp[i][b] + pre_p + p);
                ok = true;
            }
        }

        if (not ok) {
            cout << "NG " << i + 1 << endl;
            return;
        }
    }

    int ans = INF;
    FOR(b, 0, 4) {
        ans = min(ans, dp[N][b] + v.back().first);
    }
    cout << "OK " << ans << endl;
}

int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);

    while (true) {
        int N;
        cin >> N;
        if (N == 0) {
            break;
        }

        V<pair<int, int>> v(N);
        FOR(i, 0, N) {
            int p, t;
            cin >> p >> t;
            v[i] = make_pair(p, t);
        }

        solve(N, v);
    }

    return 0;
}


Measured memory_bytes: 3132