#include <iostream>
#include <vector>
 
using namespace std;
 
int main() {
    int n;
    if (!(cin >> n)) return 0; // Safe check for input
 
    vector<int> arr(n);
    for (int i = 0; i < n; i++) {
        cin >> arr[i];
    }
 
    int k;
    cin >> k;
 
    // Use a vector of pairs for cleaner syntax and better performance
    vector<pair<int, int>> ans;
 
    for (int i = 0; i < n; i++) {
        // j <= i + k already guarantees the distance is <= k
        for (int j = i + 1; j < n && j <= i + k; j++) {
            if (arr[i] == arr[j]) {
                cout << "Yes we found the valid pair" << endl;
                ans.push_back({i, j});
            }
        }
    }
 
    // Printing out the discovered pairs
    for (const auto& p : ans) {
        cout << p.first << " : " << p.second << endl;
    }
 
    return 0;
}

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