from collections import deque, defaultdict
def toposort(g,rd,n):
    path = []
    queue = deque([])
    cnt = 0
    for node in g:
        if rd[node] == 0:queue.append(node)
    while queue:
        cur = queue.popleft()
        path.append(cur)
        cnt += 1
        for child in g[cur]:
            rd[child] -= 1
            if rd[child] == 0:queue.append(child)
    flag = False
    for i in rd:
        if rd[i] > 0:
            flag = True
            break
    return [path,flag]
gdeep = 0
def dfs(node,deep,topo,vis,g):
    global gdeep
    gdeep = max(gdeep,deep)
    if vis[node] == 1:return deep 
    vis[node] = 1
    for child in g[node]:
        if vis[child] == 0 and child == topo[deep]:
            dfs(child,deep + 1,topo,vis,g)
def solve():
    n, m = map(int, input().split())
    g = defaultdict(lambda: [])
    rdfa = defaultdict(lambda: 0)
    # 如果拓扑序的长度>=n，则直接返回前n个，（注意是拓扑链条）
    # 如果无法确定关系，则优先输出有矛盾的
    for i in range(m):
        u, v = input().split('<')
        if u == v:
            return f'Inconsistency found after {i + 1} relations.'
        g[u].append(v)
        rdfa[v] += 1
        rd = rdfa.copy()
        topo,ishuan = toposort(g,rd,n)
        # 求深度
        dfs(topo[0],1,topo,defaultdict(lambda : 0),g)
        # 链条深度到达则直接返回
        if gdeep==n :
            ans = ''.join([str(x) for x in topo])
            return f'Sorted sequence determined after {i + 1} relations: {ans}.'
        if ishuan:
            return f'Inconsistency found after {i + 1} relations.'
    return 'Sorted sequence cannot be determined.'


print(solve())

测试点2的数据为

4 6
C<D
C<B
B<A
C<D
D<A
A<A

本地输出

Inconsistency found after 6 relations.

跟评测机的结果一样 但是为什么我线上评测机提示错误信息是首字母开头为S？？