#include <bits/stdc++.h>
struct node {
  int x, y;
} a[300005];
int n, m;
bool judge(int x, int y) {
  int flag = 0;
  for (int i = 0; i < m; i++) {
    if (a[i].x != x && a[i].y != y && a[i].x != y && a[i].y != x) {
      return false;
    }
  }
  return true;
}
int main() {
  int x1, x2, y1, y2;
  int i;
  scanf("%d%d", &n, &m);
  for (i = 0; i < m; i++) {
    scanf("%d%d", &a[i].x, &a[i].y);
  }
  x1 = a[0].x;
  y1 = a[0].y;
  int flag = 1;
  for (i = 1; i < m; i++) {
    if (a[i].x != x1 && a[i].y != x1 && a[i].x != y1 && a[i].y != y1) {
      x2 = a[i].x;
      y2 = a[i].y;
      flag = 0;
      break;
    }
  }
  if (flag == 1) {
    printf("YES\n");
  } else {
    if (judge(x1, x2) || judge(y1, y2) || judge(x1, y2) || judge(x2, y1) ||
        judge(x1, y1) || judge(x2, y2))
      printf("YES\n");
    else
      printf("NO\n");
  }
  return 0;
}
