全MLE求助

#include <bits/stdc++.h>
using namespace std;

inline int read(){
    int x=0,f=1;
    char ch=getchar();
    while(ch<'0'||ch>'9'){if(ch=='-') f=-1;ch=getchar();}
    while(ch>='0'&&ch<='9'){x=x*10+ch-'0';ch=getchar();}
    return x*f;
}

void write(int x){
    if(x<0){x=-x;putchar(45);}
    if(x>9) write(x/10);
    putchar(x%10+48);
    return;
}
//#include <vector>
unsigned int getXorSum(const std::vector<unsigned int>& rec) {
  unsigned ret = 0;
  for (int i = 0; i < rec.size(); ++i) ret ^= rec[i];
  return ret;
} // 将需要求按位异或和的数放在 vector 中传参。


vector<int> v[3000005];
int n, q;
int s, ans;

int main() {
    cin >> n >> q;
    for (int i = 1; i <= n; i++) {
        cin >> s;
        for (int j = 1; j <= s; j++) {
            cin >> s;
            int tmp;
            cin >> tmp;
            v[1].push_back(tmp);
        }
    }
    for (int i = 1; i <= q; i++) {
        int x, y;
        cin >> x >> y;
        ans ^= v[x][y];
    }
    cout << ans;
    // Code...

    return 0;
}