#include <iostream>
#include <vector>
#include <string>
using namespace std;
bool c[4000000];
int A,B,D,ans;
string s,d;
vector <int> V;
int main() {
cin >> A >> B >> D;
d = to_string(D);
for(int x=2; x<=B; x++) c[x] = true;
for(int x=2; x<=B; x++) {
if(c[x]) {
V.push_back(x);
for(int y=x+x; y<=B; y+=x) {
c[y]=false;
}
}
}
for(int i : V) {
if(i<A || i>B) continue;
s = to_string(i);
if(s.find(d) != string::npos) {
// cout <<s << " "<<d<<endl;
ans++;
}
}
cout<<ans;
}