#include <stdio.h>
#include <cctype>
#include <limits.h>
#include <math.h>
#include <complex>
#include <bitset>
#include <vector>
#include <map>
#include <set>
#include <stack>
#include <queue>
#include <cstring>
#include <string>
#include <sstream>
#include <algorithm>
#include <iomanip>
#include <iostream>

#define VARIABLE(x) cerr << #x << "=" << x << endl
#define BINARY(x) static_cast<bitset<16> >(x);
#define rep(i,n) for(int i=0;i<(int)(n);i++)
#define REP(i,m,n) for (int i=m;i<(int)(n);i++)
#define if_range(x, y, w, h) if (0<=(int)(x) && (int)(x)<(int)(w) && 0<=(int)(y) && (int)(y)<(int)(h))

const int INF = 1e9;
const double EPS = 1e-8;
const double PI = 3.14159;
int dx[4]={0, 1, 0, -1}, dy[4]={-1, 0, 1, 0};
using namespace std;
typedef long long ll;
//typedef pair<int, int> P;
struct P {
	int x, y, n;
	P(int n, int x, int y):n(n), x(x), y(y){}
	P(){}
};

/** Problem1306 : Ballon Collecting **/
vector<int> T, P;
int N;
int NG;
int dp[41][4];

int solve(int i, int s)
{
	if (i == N) return P[N-1];
	
	if (dp[i][s]>-1) return dp[i][s];
	
	int res=INF;
	
	int cT, cP;
	if (i==0) cT=0, cP=0;
	else	  cT=T[i-1], cP=P[i-1];
	
	bool ok=false;
	if (s+1<=3 && cT+(s+1)*abs(cP-P[i]) <= T[i]) {
		res = min(res, abs(cP-P[i])+solve(i+1, s+1));
		ok = true;
	}
	
	// 一度帰る
	if (cT+(s+1)*cP+P[i] <= T[i]) {
		res = min(res, cP+P[i]+solve(i+1, 1));
		ok = true;
	}
	
	if (!ok) NG = max(NG, i+1);
	
	return dp[i][s] = res;
}

int main()
{
	while (cin>>N, N) {
		T.resize(N), P.resize(N);
		NG = -1;
		memset(dp, -1, sizeof(dp));
		
		rep(i, N) {
			cin>>P[i]>>T[i];
		}
		int ans = solve(0, 0);
		
		if (ans < INF)
			cout << "OK " << ans << endl;
		else
			cout << "NG " << NG << endl;
	}
}