public void solve(int testNumber, InputReader in, PrintWriter out) {
int N = in.nextInt(), K = in.nextInt(), a = in.nextInt();
int M = in.nextInt();
int[] A = new int[M];
for (int i = 0; i < M; ++i) A[i] = in.nextInt();
int cnt = (N + 1) / (a + 1);
TreeSet<Integer> S = new TreeSet<>();
S.add(0);
S.add(N + 1);
for (int i = 0; i < M; ++i) {
int x = A[i];
int prev = S.lower(x), next = S.higher(x);
int ccnt = (next - prev) / (a + 1);
int ncnt = (x - prev) / (a + 1) + (next - x) / (a + 1);
cnt -= ccnt;
cnt += ncnt;
if (cnt < K) {
out.println(i + 1);
return;
}
S.add(x);
}
out.println(-1);
}
public void solve(int testNumber, InputReader in, PrintWriter out) {
int n = in.nextInt(), m = in.nextInt(), k = in.nextInt() - 1;
int pos = 0;
int[] sa = new int[m + 1], sb = new int[m + 1];
for (int i = 1; i <= m; ++i) {
sa[i] = in.nextInt() - 1;
sb[i] = in.nextInt() - 1;
}
int[] posk = new int[m + 2];
posk[m + 1] = k;
for (int i = m; i > 0; --i) {
posk[i] = posk[i + 1];
if (posk[i] == sa[i] || posk[i] == sb[i]) {
posk[i] ^= sa[i] ^ sb[i];
}
}
int pos0 = 0;
for (int i = 1; i <= m; ++i) {
if (pos0 == posk[i + 1]) {
out.println(i);
return;
}
if (pos0 == sa[i] || pos0 == sb[i]) {
pos0 ^= sa[i] ^ sb[i];
}
}
throw new RuntimeException();
}