#include <stdio.h>
#define P 0
#define N 1
int main () {
	char c;
	int stanje = P;
	while ((c=getchar())!=EOF && c!='\n') {
		if (c!='0' && c!='1') {
			printf("Greska:%c.\n",c);
			return -1;
		}
		switch(stanje) {
			case P:
				if (c=='0') stanje = N;
				else stanje = P;
				break;
			case N:
				if (c=='0') stanje = P;
				else stanje = N;
		}
	}
	if (stanje==P)
		printf("PARAN.\n");
	else
		printf("NEPARAN.\n");
	return 0;

}