func_code_string: #include <bits/stdc++.h>   using namespace std;   int main() {     ios_base::sync_with_stdio(false), cin.tie(NULL), cout.tie(NULL);     int t = 1;     while (t--) {       int n;       cin >> n;       map<int, vector<int>> m;       vector<int> v(n);       for (int i = 0; i < n; i++) {         cin >> v[i];         m[v[i]].push_back(i);       }       vector<pair<int, int>> res;       for (auto p : m) {         vector<int> tmp = p.second;         if (tmp.size() == 1) {           res.push_back(make_pair(p.first, 0));           continue;         }         int d = tmp[1] - tmp[0];         int flag = 0;         for (int i = 1; i < tmp.size() - 1; i++) {           int curr = tmp[i + 1] - tmp[i];           if (curr != d) {             flag = 1;             break;           }         }         if (flag == 1) {           continue;         }         res.push_back(make_pair(p.first, d));       }       sort((res).begin(), (res).end());       cout << res.size() << endl;       for (auto p : res) {         cout << p.first <<     << p.second << endl;       }     }     return 0;   }   