#include <stdio.h>

int main()
{
	unsigned int pocet;
	unsigned int p4 = 0;
	unsigned int p3 = 0;
	unsigned int p2 = 0;
	unsigned int p1;
	unsigned int p0;
	unsigned int c, i, path = 0;
	int ok = 1;
		

	while(scanf("%d", &pocet) != EOF)
	{
		ok = 1;
		if(pocet <= 3)
		{
			for(i = 0; i < pocet; i++)
			{
				scanf("%d", &c);
			}
			printf("OK\n");
			continue;
		}

		scanf("%d %d %d", &p2, &p1, &p0); 
 
		path = 3;
		for(i = 0; i < pocet-3; i++)
		{
			scanf("%d", &c);
			
			if (ok)
				if (p4 == 0)
					if (c > p1)
						ok = 0;
					else {path++; p4 = p3; p3 = p2; p2 = p1; p1 = p0; p0 = c;}
				else if (c > p1 - p3 && (p0 >= p2 - p4 || p0 <= p2))
					ok = 0; 
					else {path++; p4 = p3; p3 = p2; p2 = p1; p1 = p0; p0 = c;}

		}
		if (ok)
			printf("OK\n");
		else
			printf("%d\n", path);
	}

	return 0;
}