#include <bits/stdc++.h>
using namespace std;
int main() {
int n;
cin>>n;
vector<int> numbers(n);
for(auto& number: numbers){
cin>>number;
}
int distance = INT_MIN;
for(int i=0; i<n; i++){
for(int j=i+1; j<n; j++){
if(numbers[i] == numbers[j])distance = max(distance, j - i);
}
}
if(distance == INT_MIN) distance = 0;
cout<<distance;
return 0;
}
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