#!/usr/bin/env python3

n,m = map(int,input().split())
edges = [list(map(int,input().split())) for i in range(m)]

up = [i+1 for i in range(m) if edges[i][0] < edges[i][1]]
dn = [i+1 for i in range(m) if edges[i][0] > edges[i][1]]

res = up if len(up) > len(dn) else dn

print('YES')
print(len(res))
print(' '.join(map(str, res)))