include <stdio.h>

int A(int B, int C) {

int b;

while (B != 0) {
	b = B % 10;

	if (b == C) {
		return 1;
	}

	B /= 10;
}

return 0;

}

int D(int E) {

for (int i = 2; i * i <= E; i++) {

	if (E % i == 0) {
		return 0;
	}
}

return 1;

}

int main() {

int a, n, b, c = 0;
scanf("%d%d%d", &n, &b, &a);
for (; n <= b; n++) {

	if (A(n, a) == 1 && D(n)) {
		c++;
	}
}

printf("%d ", c);

}