#include <bits/stdc++.h>
using namespace std;
const int mod = 1000000007;
const int N = 600004;
const int B = 760;
long long a[N], lz[N];
pair<long long, int> b[N];
inline void upd(int l, int r, int v) {
  int lb = l / B;
  if (lz[lb]) {
    for (int i = 0; i < B; ++i) a[lb * B + i] += lz[lb];
    lz[lb] = 0;
  }
  for (int i = l; i <= r; ++i) a[i] += v;
  for (int i = 0; i < B; ++i) {
    int z = lb * B + i;
    b[z] = {a[z], z};
  }
  sort(b + lb * B, b + (lb + 1) * B);
}
int main() {
  int n, q;
  scanf("%d %d", &n, &q);
  int tb = (n - 1) / B;
  for (int i = 0; i < n; ++i) scanf("%lld", &a[i]);
  for (int k = 0; k <= tb; ++k) {
    for (int i = 0; i < B; ++i) {
      int z = k * B + i;
      b[z] = {a[z], z};
    }
    sort(b + k * B, b + (k + 1) * B);
  }
  while (q--) {
    int kn;
    scanf("%d", &kn);
    if (kn == 1) {
      int l, r, x;
      scanf("%d %d %d", &l, &r, &x);
      --l;
      --r;
      int lb = l / B, rb = r / B;
      if (lb == rb)
        upd(l, r, x);
      else {
        upd(l, B * (lb + 1) - 1, x);
        upd(B * rb, r, x);
        for (int i = lb + 1; i < rb; ++i) lz[i] += x;
      }
    } else {
      int y, mx, mn = -1;
      scanf("%d", &y);
      for (int i = 0; i <= tb; ++i) {
        int be = i * B, en = be + B;
        pair<long long, int> ks = {y - lz[i], 0};
        auto it = lower_bound(b + be, b + en, ks);
        if (b + en > it && it->first == ks.first) {
          if (mn == -1) mn = it->second;
          ks.second = mod;
          auto nt = prev(lower_bound(b + be, b + en, ks));
          mx = nt->second;
        }
      }
      printf("%d\n", mn == -1 ? -1 : mx - mn);
    }
  }
}
