怎么就错了呢？50分，其余全RE，是我思路不对吗？求回复QAQ

#include<bits/stdc++.h>
using namespace std;
const int N = 1e5 + 5;
int Q[N];
int main()
{
	int n , m , q;
	cin >> n >> m >> q;
	int ans = 0 , k = n , sum = 0;
	while(k != 0)
	{
		k /= 10;
		sum++;
	}
	while(n != m)
	{
		int a = n % 10;
		n /= 10;
		if(a != 0)
		{
			a *= a;
			a %= 10;
			n += a * pow(10 , sum - 1);
		}
		ans++;
		Q[ans] = n;
		if(ans > q)
		{
			cout << -1;
			return 0;
		}
	}
	for(int i = 1 ; i <= ans ; i++)
	{
		cout << Q[i] << endl;
	}
	return 0;
}

help me