import java.io.BufferedReader;
import java.io.IOException;
import java.io.InputStream;
import java.io.InputStreamReader;
import java.io.OutputStream;
import java.io.PrintWriter;
import java.util.ArrayList;
import java.util.Arrays;
import java.util.InputMismatchException;
import java.util.List;
import java.util.StringTokenizer;
public class Main {
public static void main(String[] args) throws IOException {
InputStream inputStream = System.in;
OutputStream outputStream = System.out;
InputReader in = new InputReader(inputStream);
PrintWriter out = new PrintWriter(outputStream);
TaskX solver = new TaskX();
solver.solve(1, in, out);
out.close();
}
static int INF = 1 << 30;
static long LINF = 1L << 55;
static int MOD = 1000000007;
static int[] mh4 = { 0, -1, 1, 0 };
static int[] mw4 = { -1, 0, 0, 1 };
static int[] mh8 = { -1, -1, -1, 0, 0, 1, 1, 1 };
static int[] mw8 = { -1, 0, 1, -1, 1, -1, 0, 1 };
static class TaskX {
int l = 1 << 19;
public void solve(int testNumber, InputReader in, PrintWriter out) {
int n = in.nextInt(), m = in.nextInt();
int[] seg = new int[l];
int[] acc = new int[l];
int[] a = new int[m], b = new int[m];
for (int i = 0; i < m; i++) {
a[i] = in.nextInt();
b[i] = in.nextInt();
}
for (int i = 0; i < m; i++) {
seg[a[i]]++;
seg[b[i]+1]--;
}
Arrays.parallelPrefix(seg, Math::addExact);
for (int i = 0; i < l; i++) {
if (seg[i] <= 1) acc[i] = 1;
}
Arrays.parallelPrefix(acc, Math::addExact);
List<Integer> list = new ArrayList<>();
for (int i = 0; i < m; i++) {
if (acc[b[i]] - acc[a[i]-1] == 0) {
list.add(i+1);
}
}
out.println(list.size());
for (int i : list) {
out.println(i);
}
}
}
static class InputReader {
BufferedReader in;
StringTokenizer tok;
public String nextString() {
while (!tok.hasMoreTokens()) {
try {
tok = new StringTokenizer(in.readLine(), " ");
} catch (IOException e) {
throw new InputMismatchException();
}
}
return tok.nextToken();
}
public int nextInt() {
return Integer.parseInt(nextString());
}
public long nextLong() {
return Long.parseLong(nextString());
}
public double nextDouble() {
return Double.parseDouble(nextString());
}
public int[] nextIntArray(int n) {
int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt();
}
return res;
}
public int[] nextIntArrayDec(int n) {
int[] res = new int[n];
for (int i = 0; i < n; i++) {
res[i] = nextInt() - 1;
}
return res;
}
public int[] nextIntArray1Index(int n) {
int[] res = new int[n + 1];
for (int i = 0; i < n; i++) {
res[i + 1] = nextInt();
}
return res;
}
public long[] nextLongArray(int n) {
long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong();
}
return res;
}
public long[] nextLongArrayDec(int n) {
long[] res = new long[n];
for (int i = 0; i < n; i++) {
res[i] = nextLong() - 1;
}
return res;
}
public long[] nextLongArray1Index(int n) {
long[] res = new long[n + 1];
for (int i = 0; i < n; i++) {
res[i + 1] = nextLong();
}
return res;
}
public double[] nextDoubleArray(int n) {
double[] res = new double[n];
for (int i = 0; i < n; i++) {
res[i] = nextDouble();
}
return res;
}
public InputReader(InputStream inputStream) {
in = new BufferedReader(new InputStreamReader(inputStream));
tok = new StringTokenizer("");
}
}
}