#include <iostream>
using namespace std;
 
int main() {
    int arr[] = {1, 1, 2, 2, 2, 1};
    int n = 6;
 
    int first[100];
    for(int i = 0; i < 100; i++) {
        first[i] = -1;
    }
 
    int Maximumdistance= 0;
 
    for(int i = 0; i < n; i++) {
        if(first[arr[i]] == -1) {
            first[arr[i]] = i;
        } else {
            int distance = i - first[arr[i]];
            if(distance > Maximumdistance)
                Maximumdistance = distance;
        }
    }
 
    cout << Maximumdistance << endl;
    return 0;
}
 

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