1 #include <iostream>
 2 using namespace std;
 3 const int MAXN = 10000 + 5;
 4 
 5 int main() {
 6     int n;
 7     cin >> n;
 8     int *p = new int[n];
 9     for (int i = 0; i < n; i++) {
10         cin >> p[i];
11     }
12     int ans[MAXN] = { 0 };
13     for (int i = 0; i < n; i++) {
14         int temp = p[i] - i - 1;
15         if (temp < 0) temp = -temp;
16         ans[temp]++;
17     }
18     for (int i = MAXN - 1; i >= 0; i--) //从大到小输出
19         if (ans[i] > 1) cout << i << " " << ans[i] << endl;
20     return 0;
21 }