import sys

data = sys.stdin.read().split()
if not data:
    sys.exit()
n = int(data[0])
m = int(data[1])
adj = [[] for _ in range(n + 1)]
idx = 2
for i in range(1, m + 1):
    u = int(data[idx])
    v = int(data[idx+1])
    idx += 2
    adj[u].append((v, i))
    adj[v].append((u, i))
tin = [-1] * (n + 1)
fup = [-1] * (n + 1)
ans = []
timer = 0
ptr = [0] * (n + 1)
stack = []
for i in range(1, n + 1):
    if tin[i] == -1:
        tin[i] = fup[i] = timer
        timer += 1
        stack.append((i, -1))
        while stack:
            v, p_e = stack[-1]
            if ptr[v] < len(adj[v]):
                to, e_idx = adj[v][ptr[v]]
                ptr[v] += 1
                
                if e_idx == p_e:
                    continue
                    
                if tin[to] != -1:
                    if tin[to] < fup[v]:
                        fup[v] = tin[to]
                else:
                    tin[to] = fup[to] = timer
                    timer += 1
                    stack.append((to, e_idx))
            else:
                stack.pop()
                if stack:
                    p_v, _ = stack[-1]
                    if fup[v] < fup[p_v]:
                        fup[p_v] = fup[v]
                    if fup[v] > tin[p_v]:
                        ans.append(p_e)
ans.sort()
print(len(ans))
if ans:
    print(*(ans))