#include <bits/stdc++.h> using namespace std; #define int long long typedef pair<int,int> P; int INF = 3e18; int mod = 1e9+7; int dx[4] = {1, 0,-1, 0}; int dy[4] = {0, 1, 0,-1}; signed main() { int N; cin >> N; vector<int>A(N); map<int,int>Mp; int ans = 0; for(int i = 0; i < N; i++) { cin >> A[i]; Mp[A[i]]++; ans = max(ans,Mp[A[i]]+Mp[A[i]+1]); ans = max(ans,Mp[A[i]]+Mp[A[i]-1]); } cout << ans << endl; }