#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) {
    map<tuple<int, int, int>, int> p_t_b;
    p_t_b[make_tuple(0, 0, 0)] = 0;

    int ans = INF;
    FOR(i, 0, N) {
        int position = v[i].first;
        int time = v[i].second;

        bool ok = false;
        map<tuple<int, int, int>, int> next_p_t;
        FOE(t, p_t_b) {
            int now_p, now_t, now_b, now_c;
            tie(now_p, now_t, now_b) = t.first;
            now_c = t.second;

            int dist = abs(position - now_p);
            if (now_t + dist * (now_b + 1) <= time and now_b + 1 <= 3) {
                // catch
                int new_cost = now_c + dist;
                auto key = make_tuple(position, time, now_b + 1);
                if (next_p_t.find(key) == next_p_t.end()) {
                    next_p_t[key] = new_cost;
                }
                else {
                    next_p_t[key] = min(next_p_t[key], new_cost);
                }

                // back
                int a = new_cost + position;
                int dt = position * (now_b + 1 + 1);

                auto key2 = make_tuple(0, time + dt, 0);
                if (next_p_t.find(key2) == next_p_t.end()) {
                    next_p_t[key2] = a;
                }
                else {
                    next_p_t[key2] = min(next_p_t[key2], a);
                }
                if (i + 1 == N) {
                    ans = min(ans, a);
                }
                ok = true;
            }
        }
        p_t_b = next_p_t;

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

    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: 3048