#include<iostream> #include<vector> #include<algorithm> using namespace std; int main(){ int n; cin >> n; vector<int> v(n); for(int i = 0; i < n; i++) cin >> v[i]; sort(v.begin(), v.end()); for(int i = 1; i < n; i++){ if(v[i]-1==v[i-1]){ cout << 2 << endl; return 0; } } cout << 1 << endl; return 0; }