我的IDE不知道怎么弄的所有编译信息都不显示，所以没法贴错误信息，如果逻辑上有错误的话各位大佬不用管，只是想知道编译为什么出错(我感觉代码好像也没什么问题啊)

/*@Unreal414 版权所有!!!*/
#include <bits/stdc++.h>
using namespace std;
string a, b;
set <string> s;
map <string, int> step;
map <int, pair <string, string> > rules;
int solve() {
    queue <string> q;
    q.push(a);
    s.insert(a);
    step[a] = 0;
    while (q.size()) {
        string &now = q.front();
        q.pop();
        if (step[now] > 10) continue;
        for (auto &e : rules) {
        	int index;
        	string next = now;
            while ((index = next.find(e.first)) <= next.size())
            	next.replace(index, index + e.first/*这里编译出错*/.size(), e/*这里编译出错*/.second);
            if (s.count(next)) continue;
            step[next] = step[now] + 1;
            s.insert(next);
            if (next == b) return step[next];
            q.push(next);
        }
    }
    return -1;
}
int main() {
	cin >> a >> b;
	while (cin >> rules[rules.size()].first >> rules[rules.size() - 1].second) {}
	int result = solve();
	if (result == -1) {
		cout << "NO ANSWER!";
		return 0;
	}
	cout << result << "\n";
	return 0;
}