#include <bits/stdc++.h>
using namespace std;
const int max_n = 500 * 1000, max_sq = 1000;
long long a[max_n];
long long shift[max_sq];
multiset<long long> S[max_sq];
int main() {
  int n, q;
  scanf("%d%d", &n, &q);
  const int sq = min(sqrt(n), 700.);
  for (int i = 0; i < (n); i++) {
    int x;
    scanf("%d", &x);
    a[i] = x;
    S[i / sq].insert(a[i]);
  }
  memset(shift, 0, sizeof shift);
  while (q--) {
    int k;
    scanf("%d", &k);
    if (k == 1) {
      int l, r, x;
      scanf("%d%d%d", &l, &r, &x);
      l--, r--;
      for (int i = l; i <= r; i = (i / sq + 1) * sq)
        if (i % sq == 0 && i + sq - 1 <= r)
          shift[i / sq] += x;
        else
          for (int j = i; j <= r && j < (i / sq + 1) * sq; j++) {
            S[i / sq].erase(S[i / sq].find(a[j]));
            S[i / sq].insert(a[j] + x);
            a[j] += x;
          }
    } else {
      int y;
      scanf("%d", &y);
      int l = n + 1, r = n;
      for (int i = 0; i * sq < n && l == n + 1; i++)
        if (S[i].count(y - shift[i]))
          for (int j = i * sq; j < (i + 1) * sq; j++)
            if (a[j] == y - shift[i]) {
              l = j;
              break;
            }
      for (int i = (n - 1) / sq; i >= 0 && r == n; i--)
        if (S[i].count(y - shift[i]))
          for (int j = min((i + 1) * sq, n) - 1; j >= i * sq; j--)
            if (a[j] == y - shift[i]) {
              r = j;
              break;
            }
      printf("%d\n", r - l);
    }
  }
  return 0;
}
