#include <bits/stdc++.h>
using namespace std;
const int SQ = 700;
vector<pair<long long, long long> > vec[SQ * 10];
long long lz[SQ * 10];
int n, q;
void add(int l, int r, long long x) {
  int ind[2] = {l / SQ, r / SQ};
  for (int i = 0; i < (int)vec[ind[0]].size(); i++)
    if (vec[ind[0]][i].second >= l && vec[ind[0]][i].second <= r)
      vec[ind[0]][i].first += x;
  for (int i = ind[0] + 1; i < ind[1]; i++) lz[i] += x;
  if (ind[0] != ind[1])
    for (int i = 0; i < (int)vec[ind[1]].size(); i++)
      if (vec[ind[1]][i].second >= l && vec[ind[1]][i].second <= r)
        vec[ind[1]][i].first += x;
  sort(vec[ind[0]].begin(), vec[ind[0]].end());
  sort(vec[ind[1]].begin(), vec[ind[1]].end());
}
int get(long long x) {
  pair<int, int> ans = {-1, -2};
  for (int i = 0; i < n; i += SQ) {
    int ind = i / SQ;
    if (ans.first == -1) {
      int k = lower_bound(vec[ind].begin(), vec[ind].end(),
                          make_pair(x - lz[ind], -1LL)) -
              vec[ind].begin();
      if (0 <= k && k < (int)vec[ind].size() &&
          vec[ind][k].first == x - lz[ind])
        ans.first = vec[ind][k].second;
    }
    int k = lower_bound(vec[ind].begin(), vec[ind].end(),
                        make_pair(x - lz[ind] + 1, -1LL)) -
            vec[ind].begin() - 1;
    if (0 <= k && k < (int)vec[ind].size() && vec[ind][k].first == x - lz[ind])
      ans.second = vec[ind][k].second;
  }
  return ans.second - ans.first;
}
int main() {
  ios::sync_with_stdio(false), cin.tie(0), cout.tie(0);
  ;
  cin >> n >> q;
  for (int i = 0; i < n; i++) {
    long long a;
    cin >> a;
    vec[i / SQ].push_back({a, i});
  }
  for (int i = 0; i < n; i += SQ) sort(vec[i / SQ].begin(), vec[i / SQ].end());
  while (q--) {
    int ty;
    cin >> ty;
    if (ty == 1) {
      long long l, r, x;
      cin >> l >> r >> x;
      add(l - 1, r - 1, x);
    } else {
      long long y;
      cin >> y;
      cout << get(y) << endl;
    }
  }
  return 0;
}
