func_code_string: #include <bits/stdc++.h>   using namespace std;   void mego() {     ios::sync_with_stdio(0);     cin.tie(0);     cout.tie(0);   }   bool isp(long long x) {     for (long long i = 2; i * i <= x; i++)       if (!(x % i)) return false;     return true;   }   long long coun = 0;   int gcd(long long a, long long b) {     if (b == 0) return a;     coun += (a / b);     return gcd(b, a % b);   }   int main() {     mego();     long long n, a, z = 0, b = 0, d = 0, c = 0;     vector<long long> v, v1;     long long t = 0;     cin >> t;     map<int, pair<int, int> > ma;     for (int i = 1; i <= t; i++) {       cin >> a;       if (!ma[a].first) {         ma[a].first = i;       } else if (!ma[a].second)         ma[a].second = i;       else {         if ((i - ma[a].second) != (ma[a].second - ma[a].first)) {           ma[a].first = -1;           ma[a].second = -1;         } else {           ma[a].first = ma[a].second;           ma[a].second = i;         }       }     }     vector<pair<int, int> > vp;     pair<int, int> rej = {-1, -1};     for (auto it : ma) {       if (it.second != rej) {         vp.push_back(make_pair(it.first, it.second.second - it.second.first));       }     }     cout << vp.size() <<   n ;     for (int i = 0; i < vp.size(); i++) {       cout << vp[i].first <<     << (vp[i].second > 0 ? vp[i].second : 0) <<   n ;     }     return 0;   }   