#include <bits/stdc++.h>
using namespace std;
const char eol = '\n';
int const bs = 500;
int n;
int bc;
vector<long long> val;
vector<vector<int> > blo;
vector<long long> add;
bool cmp(int A, int B) {
  if (val[A] != val[B]) return val[A] < val[B];
  return A < B;
}
void sortBlock(int i) { sort(blo[i].begin(), blo[i].end(), cmp); }
void init(vector<int> a) {
  n = int(a.size());
  val = vector<long long>(n);
  for (int i = 0; i < (n); ++i) val[i] = a[i];
  bc = n / bs;
  if (n % bs != 0) bc += 1;
  blo = vector<vector<int> >(bc);
  for (int i = 0; i < (n); ++i) {
    blo[i / bs].push_back(i);
  }
  for (int i = 0; i < (bc); ++i) {
    sortBlock(i);
  }
  add = vector<long long>(bc);
}
void inc(int l, int r, int x) {
  if (l / bs == r / bs) {
    for (int i = l; i < (r + 1); ++i) val[i] += x;
    sortBlock(l / bs);
    return;
  }
  for (int i = l; i < ((l / bs + 1) * bs); ++i) val[i] += x;
  sortBlock(l / bs);
  for (int i = l / bs + 1; i < (r / bs); ++i) add[i] += x;
  for (int i = (r / bs) * bs; i < (r + 1); ++i) val[i] += x;
  sortBlock(r / bs);
}
int getmax(int i, long long y) {
  y -= add[i];
  int l = 0, r = int(blo[i].size());
  while (l < r) {
    int m = (l + r) / 2;
    if (val[blo[i][m]] <= y)
      l = m + 1;
    else
      r = m;
  }
  l -= 1;
  if (l == -1 || val[blo[i][l]] != y) return -1;
  return blo[i][l];
}
int getmin(int i, long long y) {
  y -= add[i];
  int l = 0, r = int(blo[i].size());
  while (l < r) {
    int m = (l + r) / 2;
    if (val[blo[i][m]] < y)
      l = m + 1;
    else
      r = m;
  }
  if (l == int(blo[i].size()) || val[blo[i][l]] != y) return n;
  return blo[i][l];
}
int get(int y) {
  int mx = -1;
  int mn = n;
  for (int i = 0; i < (bc); ++i) {
    mx = max(mx, getmax(i, y));
    mn = min(mn, getmin(i, y));
  }
  return mx == -1 ? -1 : mx - mn;
}
int main() {
  ios_base::sync_with_stdio(false);
  cin.tie(0);
  cout << fixed << setprecision(10);
  int N, M;
  cin >> N >> M;
  vector<int> a(N);
  for (int i = 0; i < (N); ++i) cin >> a[i];
  init(a);
  while (M--) {
    int q;
    cin >> q;
    if (q == 1) {
      int l, r, x;
      cin >> l >> r >> x;
      inc(l - 1, r - 1, x);
    } else if (q == 2) {
      int y;
      cin >> y;
      cout << get(y) << eol;
    } else {
      assert(false);
    }
  }
  return 0;
}
