RT，用快读会UKE，但是把读入n那一行改成 cin >> n就A了（我知道这里快读没意义，想知道原因

#include <iostream>
#include <cstdio>
#include <cstring>
using namespace std;
#define rg register
inline int read(){
    rg int x = 0, f = 1;
    rg char c = getchar();
    while (c < '0' || c > '9') {if (c == '-') f = -1; c = getchar();}
    while (c >= '0' && c <= '9') x = (x << 1) + (x << 3) + (c ^ 48), c = getchar();
    return x * f;
}
const int N = 1e6 + 1;
int n;
int net[N];
int prenext(string a){
    net[0] = 0;
    int len = a.length();
    for (int i = 1; i < len; ++i){
        int j = net[i - 1];
        while (j && a[j] != a[i]) j = net[j - 1];
        if (a[j] == a[i]) net[i] = j + 1;
        else net[i] = 0;
    }
    return net[len - 1];
}

inline void doit(){
    n = read();
    string b, ans;
    cin >> ans;
    for (int i(2); i <= n; ++i){
        cin >> b;
        int l = min(b.size(), ans.size());
        string a = b + "#" + ans.substr(ans.size() - l, l);
        b.erase(0, prenext(a));
        ans += b;
    }
    cout << ans;
}
int main(){
    ios::sync_with_stdio(false);
    cin.tie(0),cout.tie(0);
    //freopen("in.txt", "r", stdin);
    doit();
    return 0;
}