#include <bits/stdc++.h>
using namespace std;
int n, q, m, t, N;
int a[505555], b[1111], inf = 1000000001;
set<pair<int, int> > A[1111];
set<pair<int, int> >::iterator it;
void upd(int l, int r, int x) {
  for (int i = l; i <= r;)
    if (i % m == 0 && i + m <= r) {
      if (b[i / m] < inf) b[i / m] += x;
      i += m;
    } else {
      if (a[i] < inf) {
        A[i / m].erase(A[i / m].lower_bound(make_pair(a[i], i)));
        a[i] += x;
        if (a[i] < inf) A[i / m].insert(make_pair(a[i], i));
      }
      i++;
    }
}
int X;
int found(int ind, int y) {
  X = -1;
  it = A[ind].lower_bound(make_pair(y, -1));
  if (it->first == y) X = it->second;
  return X;
}
int Found(int ind, int y) {
  X = -1;
  it = A[ind].lower_bound(make_pair(y, 1111111));
  if ((it != A[ind].begin()) && ((--it)->first == y)) X = it->second;
  return X;
}
int ft, last;
void show(int y) {
  ft = -1, last = -2;
  for (int i = 0; i < t; i++)
    if (!A[i].empty()) {
      it = A[i].begin();
      if (b[i] + (it->first) <= y) {
        ft = found(i, y - b[i]);
        if (ft + 1) break;
      }
    }
  if (ft > -1)
    for (int i = t - 1; i >= 0; i--)
      if (!A[i].empty()) {
        it = A[i].begin();
        if (b[i] + (it->first) <= y) {
          last = Found(i, y - b[i]);
          if (last + 1) break;
        }
      }
  printf("%d\n", last - ft);
}
int main() {
  scanf("%d %d\n", &n, &q);
  m = (int)sqrt(n);
  for (int i = 0; i < n; i++) {
    scanf("%d ", a + i);
    A[i / m].insert(make_pair(a[i], i));
  }
  t = n / m + 1;
  int l, r, x, c;
  scanf("\n");
  while (q--) {
    scanf("%d ", &c);
    if (c == 1) {
      scanf("%d %d %d\n", &l, &r, &x);
      l--, r--;
      upd(l, r, x);
    } else {
      scanf("%d\n", &x);
      show(x);
    }
  }
  return 0;
}
