#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <deque>
#include <iomanip>
#include <iostream>
#include <numeric>
#include <optional>
#include <queue>
#include <set>
#include <stack>
#include <unordered_map>
#include <unordered_set>
#include <vector>

using namespace std;

int main() {
    int32_t n;
    cin >> n;
    vector<int32_t> as(n);
    for (auto &&a : as) {
        cin >> a;
    }
    sort(as.begin(), as.end());
    bool c = false;
    for (auto i = 0; i < n - 1; ++i) {
        if (as[i] + 1 == as[i + 1])
            c = true;
    }
    cout << 1 + int32_t(c) << endl;
    return 0;
}