#include <stdio.h>
#include <stdlib.h>

typedef struct position {
	int x;
	int y;
}Position;

int main() {
	int N, i = 0,  j, found = 0, k, numOfSteps = 0, tisicaKonstanta = 0, kos, p;	
	Position position;
	position.x = 0;
	position.y = 0;
	Position *pole;
	int *readNumber;

	while ( scanf("%d", &N) > 0 ) {
		pole = (Position*) malloc (sizeof(Position)*1000000000);
		found = numOfSteps = tisicaKonstanta = i = 0;
		pole[tisicaKonstanta].x = 0;
		pole[tisicaKonstanta].y = 0;
		tisicaKonstanta++;
		readNumber = (int*) malloc (sizeof(int)*N);
		for ( p = 0; p < N; p++ ) { 
			scanf("%d", &readNumber[p]);
		}
		
		while ( i < N && found == 0) {
			numOfSteps += readNumber[i]; 
			//nastavi x a y noveho bodu ... funguje .. 
			for ( k = 0; k < readNumber[i]; k++ ) {
				switch ( i % 4 ) { 
					case 0:
						position.y++;
						break;
					case 1:
						//pole = (Position) realloc (pole, sizeof(pole)+readNumber);
						position.x++;// readNumber;
						break;
					case 2:
						//pole = (Position) realloc (pole, sizeof(pole)+readNumber);
						position.y--;// readNumber;
						break;
					case 3:
						//pole = (Position) realloc (pole, sizeof(pole)+readNumber);
						position.x--;// readNumber;
						break;
				}
				for ( j = 0; j < numOfSteps; j++ ) {
					if ( pole[j].x == position.x && pole[j].y == position.y ) {
						found = 1;
						
					}
				}
				if ( found == 0 ) {
					
					pole[tisicaKonstanta].x = position.x;
					pole[tisicaKonstanta++].y = position.y;
				}	
			
			}
			i++;
		}
		//toto by malo byt v poriadku .. 
		i--;
		if ( found == 1 ) {
			printf("%d\n",i);
		}
		else 
		{	
			printf("OK\n");
		}
		i++;
		//while ( scanf("%d", &kos) != 0 ); 
	}	
	return 0;
}