123

#include <iostream>
#include<cmath>
using namespace std;

int main() {
	int A, B, D, count = 0, flage;
	scanf("%d%d%d", &A, &B, &D);
	for (int i = A; i <= B; i++) {
		flage = 0;
		for (int j = 2; j<=sqrt(i); j++) {
			if (i % j == 0) {
				flage++;
				break;
			}
		}
		int e = i;
		if (flage == 0) {
			while (e > 0) {
				int o = e % 10;
				e = e / 10;
				if (o == D) {
					count++;
					break;
				}
			}
		}
	}
	printf("%d",count);
	return 0;

}