#include <iostream>
#include <cmath>
#include <vector>
#include <map>
#include <set>
#include <queue>
#include <sstream>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <string>
#include <algorithm>

using namespace std;

typedef long long int ll;
typedef unsigned long long int ull;
typedef pair<int, int> pii;

#define PB push_back
#define MP make_pair

#define FOR(prom, a, b) for(int prom = (a); prom < (b); prom++)
#define FORD(prom, a, b) for(int prom = (a); prom > (b); prom--)
#define FORDE(prom, a, b) for(int prom = (a); prom >= (b); prom--)

#define MM(co, cim) memset((co), (cim), sizeof((co)))
#define DEB(x) cerr << ">>> " << #x << " : " << x << endl;

#define MAXA 1000001000



char nextSmer ( char s ) {
	switch ( s ) {
		case 'U': return 'R';
		case 'R': return 'D';
		case 'D': return 'L';
		case 'L': return 'U';
	}
	return 'X';
}

int main ( void )
{
	int N, A;
	
	while ( scanf( "%d", &N ) == 1 ) {
		char smer = 'U';
	
		int posX, posY;
		posX = posY = 0;
			
		int minX, maxX, minY, maxY;
		maxX = maxY = MAXA;
		minX = minY = -MAXA;
		
		int prevXX, prevXY, prev2XX, prev2XY;
		int prevYX, prevYY, prev2YX, prev2YY;
		
		prevXX = prevXY = prev2XX = prev2XY = 0;
		prevYX = prevYY = prev2YX = prev2YY = 0;
		
		if ( N <= 3 ) {
			printf("OK\n");
			for ( int n = 0; n < N; n++ )
				scanf( "%d", &A );
			continue;
		}
		
		bool ok = true;
		for ( int n = 0; n < N; n++ ) {
			scanf( "%d", &A );
			if ( !ok ) continue;
			
			switch ( smer ) {
				case 'U':
					if ( posY + A >= maxY ) {
						printf( "%d\n", n );
						ok = false;
						break;						
					} else if ( posY + A <= prevXY ) {
						minX = posX;
						minY = posY;
						maxY = posY + A;
					
						if ( posY + A >= prev2XY ) {
							maxX = prev2XX;
						} else {
							maxX = prevXX;
						}
					}
					
					break;
				case 'R':
					if ( posX + A >= maxX ) {
						printf( "%d\n", n );
						ok = false;
						break;						
					} else if ( posX + A <= prevYX ) {
						maxY = posY;
						minX = posX;
						maxX = posX + A;
					
						if ( posX + A >= prev2YX ) {
							minY = prev2YY;
						} else {
							minY = prevYY;
						}
					}
				
					break;
				case 'D':
					if ( posY - A <= minY ) {
						printf( "%d\n", n );
						ok = false;
						break;						
					} else if ( posY - A >= prevXY ) {
						maxX = posX;
						maxY = posY;
						minY = posY - A;
					
						if ( posY - A <= prev2XY ) {
							minX = prev2XX;
						} else {
							minX = prevXX;
						}
					}
					
					break;
				case 'L':
					if ( posX - A <= minX ) {
						printf( "%d\n", n );
						ok = false;
						break;						
					} else if ( posX - A >= prevYX ) {
						minY = posY;
						maxX = posX;
						minX = posX - A;
					
						if ( posX - A <= prev2YX ) {
							maxY = prev2YY;
						} else {
							maxY = prevYY;
						}
					}
					
					break;
			}
			
			switch ( smer ) {
				case 'U':
				case 'D':
					prev2XX = prevXX;
					prev2XY = prevXY;
					
					prevXX = posX;
					prevXY = posY;
					break;
				case 'R':
				case 'L':
					prev2YX = prevYX;
					prev2YY = prevYY;
					
					prevYX = posX;
					prevYY = posY;
					break;
			}
			
			switch ( smer ) {
				case 'U':
					posY = posY + A;	
					break;
				case 'R':
					posX = posX + A;
					break;
				case 'D':
					posY = posY - A;
					break;
				case 'L':
					posX = posX - A;
					break;
			}
			
			smer = nextSmer( smer );
					
			/*
			cerr << "pos = [" << posX << "," << posY << "]" << endl
				 << "boundX = [ " << minX << "," << maxX << "]" << endl
				 << "boundY = [ " << minY << "," << maxY << "]" << endl
				 << "prevX [" << prevXX << "," << prevXY << "] -> [" << prev2XX << "," << prev2XY << "]" << endl
				 << "prevY [" << prevYX << "," << prevYY << "] -> [" << prev2YX << "," << prev2YY << "]" << endl
				 << "-------" << endl;
				 /*
			DEB( posX );
			DEB( posY );
			DEB( prevXX ); DEB( prevXY );
			DEB( prev2XX ); DEB( prev2XY );
			DEB( minX ); DEB( maxX );
			DEB( minY ); DEB( maxY );//*/
		}
		
		if ( ok ) {
			printf( "OK\n" );		
		}		
	}
	
	return 0;
}