#include <iostream>
using namespace std;
int main(void) {
int n, a, d;
int answer = 0;
int current;
int idx = 0;
int input;
ios_base::sync_with_stdio(false);
cin.tie(0);
cout.tie(0);
cin >> n >> a >> d;
for (int i = 0; i < n; i++) {
cin >> input;
current = a + idx * d;
if (current == input) {
idx++;
answer++;
}
}
cout << answer;
return (0);
}