rt， 只要把第28行的cnt++改为++cnt即可让程序从输出错误答案变成exe停止工作

大为不解， 希望有大佬帮助
以下为代码：

#include <iostream>
#include <algorithm>
#include <vector>
#include <stack>
#include <bitset>

using namespace std;

const int M = 1e5 + 10;
const int N = 1e4 + 10;

std::vector<int> graph[M];
std::vector<int> belong[N];
std::stack<int> st;
int n, m;
int dfn[M], low[M], cnt;
bitset<N> instack;
int p;
bitset<N> is_print;

void tarjan(int u, int fa)
{
	dfn[u] = low[u] = cnt++;
	st.push(u);
	instack[u] = true;
	for(int n : graph[u])
	{
		if(n == fa)
		{
			fa = -1;
			continue;
		}
		if(dfn[n] == 0)
		{
			tarjan(n, u);
			low[u] = std::min(low[u], low[n]);
		}
		else if(instack[n])
		{
			low[u] = std::min(low[u], dfn[n]);
		}
		
		if(dfn[u] == low[u])
		{
			++p;
			while(st.top() != u)
			{
				belong[p].push_back(st.top());
				instack[st.top()] = false;
				st.pop();
			}
			belong[p].push_back(u);
			instack[st.top()] = false;
			st.pop();
			std::sort(belong[p].begin(), belong[p].end());
		}
		
	}
	
}

int main()
{
	scanf("%d %d", &n, &m);
	for(int u, v, i = 1;i <= m;i ++)
	{
		scanf("%d %d", &u, &v);
		graph[u].push_back(v);
	}
	tarjan(1, -1);
	
	printf("%d\n", p);
	for(int i = 1;i <= p;i ++)
	{
		for(int j : belong[i])
			printf("%d ", j);
		putchar('\n');
	}
	
	return 0;
}