func_code_string: #include <bits/stdc++.h>   using namespace std;   int blk_size;   struct node {     int l, r, id;     long long int ans = 0;   };   bool compare(node a, node b) {     if (a.l / blk_size != b.l / blk_size)       return (a.l) / blk_size < (b.l) / blk_size;     return a.r < b.r;   }   bool compare2(node a, node b) { return a.id < b.id; }   long long int freq[3000001];   int main() {     ios_base::sync_with_stdio(false);     ;     int n, m, k;     cin >> n >> m >> k;     std::vector<int> a(n), pxor(n + 1);     for (int i = 0; i < n; i++) cin >> a[i];     pxor[0] = 0;     for (int i = 1; i <= n; i++) pxor[i] = pxor[i - 1] ^ a[i - 1];     blk_size = sqrt(n + 1);     std::vector<node> q(m);     for (int i = 0; i < m; i++) {       cin >> q[i].l >> q[i].r;       q[i].id = i;     }     sort(q.begin(), q.end(), compare);     int start = 0, end = 0;     long long int ans = 0;     freq[0] = 1;     for (int i = 0; i < m; i++) {       int l = q[i].l - 1, r = q[i].r;       while (start > l) {         start--;         ans += freq[pxor[start] ^ k];         freq[pxor[start]]++;       }       while (start < l) {         freq[pxor[start]]--;         ans -= freq[pxor[start] ^ k];         start++;       }       while (end > r) {         freq[pxor[end]]--;         ans -= freq[pxor[end] ^ k];         end--;       }       while (end < r) {         end++;         ans += freq[pxor[end] ^ k];         freq[pxor[end]]++;       }       q[i].ans = ans;     }     sort(q.begin(), q.end(), compare2);     for (int i = 0; i < m; i++) cout << q[i].ans <<   n ;     return 0;   }   