// Enjoy your stay. Code by evima

#include <bits/stdc++.h>
using namespace std;

using ld = long double;
using ll = long long;
using vl = vector<ll>;
using LOOPVAR_TYPE = ll;

#define all(x) (x).begin(), (x).end()
#define sz(x) ll((x).size())
#define GET_MACRO(_1, _2, _3, NAME, ...) NAME
#define rep1(i, n) rep2(i, 0, n)
#define rep2(i, a, b) for(LOOPVAR_TYPE i = LOOPVAR_TYPE(a); i < LOOPVAR_TYPE(b); i++)
#define rep(...) GET_MACRO(__VA_ARGS__, rep2, rep1)(__VA_ARGS__)

template<class T> bool chmin(T& a, const T& b) { return (b < a) ? (a = b, true) : false; }
template<class T> bool chmax(T& a, const T& b) { return (a < b) ? (a = b, true) : false; }

#define eb emplace_back
#define fir first
#define sec second

const ld EPS = 1e-9;
const ld PI = 3.14159265358979323846L;
const ll INF = 1070000000LL;
const ll MOD = 998244353LL;// 1000000007LL;

void fast_io() { cin.tie(NULL); ios_base::sync_with_stdio(false); }
ll ll_input() { ll x; cin >> x; return x; }
string input() { string s; cin >> s; return s; }
vl vl_input(int n) { vector<ll> v(n); rep(i, n) cin >> v[i]; return v; }
template<class T> vector<T> sub(const vector<T>& v, int from, int to) { vector<T> ret; copy(&v[from], &v[to], back_inserter(ret)); return ret; }
template<class T> string str(const T& x) { stringstream ss; ss << x; return ss.str(); }
template<class T> string str(const vector<T>& v) { stringstream ss; rep(i, sz(v)) ss << v[i] << (i < sz(v) - 1 ? " " : ""); return ss.str(); }
template<class T> void print1(T&& x, const string& end) { cout << str(x) << end; }
void print() { print1("", "\n"); }
template<class T, class... U> void print(T&& head, U&&... tail) { print1(head, " "); print(forward<U>(tail)...); }
template<class... T> void quit(T&&... x) { print(forward<T>(x)...); exit(0); }



void solveOne(){
    ll N = ll_input();
    auto A = vl_input(N);
    rep(i, N - 1){
        if(A[i] + 1 == A[i + 1]) quit(2);
    }
    print(1);
}

int main(){
    fast_io();
    
    int num_tc = 1;
    // cin >> num_tc;
    
    
    
    rep(tc, 1, num_tc + 1){
        // cout << "Case #" << tc << ": " ;// << endl;
        solveOne();
    }
}