func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAX = 100000 + 10;   int pos[MAX], s[MAX];   int main() {     int n, a;     while (cin >> n) {       memset(pos, 0, sizeof pos);       memset(s, -1, sizeof s);       for (int i = 1; i <= n; ++i) {         cin >> a;         if (s[a] == -1)           s[a] = 0;         else if (s[a] == 0)           s[a] = i - pos[a];         else if (s[a] > 0 && i - pos[a] != s[a])           s[a] = -2;         pos[a] = i;       }       int sum = 0;       for (int i = 1; i < MAX; ++i)         if (s[i] >= 0) ++sum;       cout << sum << endl;       for (int i = 1; i < MAX; ++i) {         if (s[i] >= 0) cout << i <<     << s[i] << endl;       }     }     return 0;   }   