#include <iostream>
#include <fstream>
using namespace std;
ifstream f("lungime.in");
ofstream g("lungime.out");
int i, n, L, num, vc[100], primaap[100], lung;
int main()
{
f >> n;
for (i=1; i<=n; ++i)
{
f >> num;
if (vc[num]==0)
{
vc[num]=1; primaap[num]=i; }
else
{
lung=i-primaap[num]+1;
if (lung>L) L=lung;
}
}
g << L;
}