#include <bits/stdc++.h>
using namespace std;
#define SZ(x) (int)(x.size())
#define REP(i, n) for(int i=0;i<(n);++i)
#define FOR(i, a, b) for(int i=(a);i<(b);++i)
#define RREP(i, n) for(int i=(int)(n)-1;i>=0;--i)
#define RFOR(i, a, b) for(int i=(int)(b)-1;i>=(a);--i)
#define ALL(a) a.begin(),a.end()
#define DUMP(x) cerr<<#x<<" = "<<(x)<<endl
#define DEBUG(x) cerr<<#x<<" = "<<(x)<<" (L"<<__LINE__<<")"<< endl;
using ll = long long;
using vi = vector<int>;
using vvi = vector<vi>;
using vll = vector<ll>;
using vvll = vector<vll>;
using P = pair<int, int>;
const double eps = 1e-8;
const ll MOD = 1000000007;
const int INF = INT_MAX / 2;
const ll LINF = LLONG_MAX / 2;
template <typename T1, typename T2>
bool chmax(T1 &a, const T2 &b) {
    if (a < b) { a = b; return true; }
    return false;
}
template <typename T1, typename T2>
bool chmin(T1 &a, const T2 &b) {
    if (a > b) { a = b; return true; }
    return false;
}
template<typename T>
ostream &operator<<(ostream &os, const vector<T> &v) {
    os << "[";
    REP(i, SZ(v)) {
        if (i) os << ", ";
        os << v[i];
    }
    return os << "]";
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const map<T1, T2> &mp) {
    os << "{";
    int a = 0;
    for (auto &tp : mp) {
        if (a) os << ", "; a = 1;
        os << tp;
    }
    return os << "}";
}
template<typename T1, typename T2>
ostream &operator<<(ostream &os, const pair<T1, T2> &p) {
    os << p.first << ":" << p.second;
    return os;
}


int main() {
    cin.tie(0);
    ios::sync_with_stdio(false);
    cout << fixed << setprecision(10);

    for (;;) {
        int n; cin >> n;
        if (n == 0) break;
        vi p(n), t(n);
        REP(i, n) cin >> p[i] >> t[i];
        vvi dp(3, vi(n, INF));

        if (t[0] < p[0]) {
            cout << "NG 1" << endl;
            continue;
        }
        dp[0][0] = p[0];
        bool valid = true;
        FOR(i, 1, n) {
            if (dp[0][i-1] != INF) {
                if (t[i-1] + 2 * p[i-1] + p[i] <= t[i]) {
                    chmin(dp[0][i], dp[0][i-1] +
                        p[i-1] + p[i]);
                }
                if (t[i-1] + 2 * abs(p[i-1] - p[i]) <= t[i]) {
                    chmin(dp[1][i], dp[0][i-1] +
                                    abs(p[i-1] - p[i]));
                }
            }
            if (dp[1][i-1] != INF) {
                if (t[i-1] + 3 * p[i-1] + p[i] <= t[i]) {
                    chmin(dp[0][i], dp[1][i-1] +
                                    p[i-1] + p[i]);
                }
                if (t[i-1] + 3 * abs(p[i-1] - p[i]) <= t[i]) {
                    chmin(dp[2][i], dp[1][i-1] +
                                    abs(p[i-1] - p[i]));
                }
            }
            if (dp[2][i-1] != INF) {
                if (t[i-1] + 4 * p[i-1] + p[i] <= t[i]) {
                    chmin(dp[0][i], dp[2][i-1] +
                                    p[i-1] + p[i]);
                }
            }
            if (dp[0][i] == INF and
                dp[1][i] == INF and
                dp[2][i] == INF) {
                valid = false;
                cout << "NG " << i+1 << endl;
                break;
            }
        }
        if (!valid) continue;
        cout << "OK " << min({
            dp[0][n-1], dp[1][n-1], dp[2][n-1]}) + p[n-1] << endl;
    }

    return 0;
}



Measured memory_bytes: 3184