#include <bits/stdc++.h>
using namespace std;
const int INF = 0x3f3f3f3f;
const double eps = 1e-9;
int n, m, l, r;
int main() {
  int T, cas = 1, x = INF;
  scanf("%d%d", &n, &m);
  for (int i = 1; i <= m; ++i) {
    scanf("%d%d", &l, &r);
    x = min(x, r - l + 1);
  }
  printf("%d\n", x);
  for (int i = 1; i <= n; ++i) printf("%d%c", i % x, i == n ? '\n' : ' ');
  return 0;
}
