#include <algorithm>
#include <array>
#include <cmath>
#include <cstdio>
#include <iostream>
#include <numeric>
#include <optional>
#include <vector>

using namespace std;

int main() {
    int32_t n, m;
    cin >> n >> m;
    vector<int32_t> v(n);
    for (auto i = 0; i < n; ++i)
        v[i] = n - i;
    for (auto i = 0; i < m; ++i) {
        int32_t a;
        cin >> a;
        --a;
        int32_t index = n - a - 1;
        auto x = v[index];
        v.erase(v.begin() + index);
        v.push_back(x);
    }
    cout << v.back() << endl;
    return 0;
}