#include <stdio.h>

struct Yoba {
	struct Peka *peka;
};

struct Peka {
	struct Yoba *yoba;
};

int main(void) {
	struct Yoba y;
	struct Peka p;
	y.peka = &p;
	p.yoba = &y;
	printf("OK\n");
	return 0;
}