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#include<iostream>
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#include<string>
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#include<string.h>
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#include<vector>
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#include<queue>
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#include<map>
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#include<stack>
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#include<set>
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#include<functional>
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#include<utility>
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#include<algorithm>
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#include<cmath>
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#include<climits>
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#include<tuple>
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#include<numeric>
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#include<any>
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#include<bitset>
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#define int long long
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using namespace std;
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const int N = 1e5 + 10, M = 31;
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int n, m, maxx;
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vector<int> numb(M);
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map<vector<int>, int> mp;
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signed main() {
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  cin.tie(nullptr)->ios::sync_with_stdio(false);
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  cin >> n >> m;
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  mp[vector<int>(M)] = 0;
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  for (int i = 1;i <= n;i++) {
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    int num;
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    cin >> num;
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    bitset<M> bs(num);
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    for (int j = 0;j < M;j++)
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      numb[j] += bs[j];
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    vector<int> cz(M);
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    for (int i = 0;i < m;i++)
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      cz[i] = numb[i] - numb[0];
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    if (mp.count(cz))
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      maxx = max(i - mp[cz], maxx);
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    else mp[cz] = i;
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  }
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  cout << maxx;
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  return 0;
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}