#include <bits/stdc++.h>
using namespace std;
long long offset[1000];
vector<pair<long long, int> > x[1000];
long long v[500005];
int bucketsize = 700;
inline int bucket(int x) { return x / bucketsize; }
int buckets, n;
inline int bstart(int x) {
  if (x == buckets + 1) {
    return n + 1;
  }
  return x * bucketsize;
}
void resort(int buc) {
  x[buc].clear();
  int l = bstart(buc), r = bstart(buc + 1);
  for (int j = l; j < r; j++) {
    x[buc].push_back({v[j], j});
  }
  sort(x[buc].begin(), x[buc].end());
}
int main() {
  int q;
  scanf("%d %d", &n, &q);
  buckets = bucket(n);
  for (int i = 1; i <= n; i++) {
    int k;
    scanf("%d", &k);
    v[i] = k;
    x[bucket(i)].push_back({v[i], i});
  }
  for (int i = 0; i <= buckets; i++) {
    resort(i);
  }
  for (int qq = 0; qq < q; qq++) {
    int t;
    scanf("%d", &t);
    if (t == 1) {
      int l, r, dd;
      scanf("%d %d %d", &l, &r, &dd);
      long long d = dd;
      int lbucket0 = bucket(l);
      int lbucket1 = lbucket0 + 1;
      int rbucket = bucket(r);
      int lstart1 = bstart(lbucket1);
      for (int j = lbucket1; j < rbucket; j++) {
        offset[j] += d;
      }
      if (lbucket0 == rbucket) {
        for (int j = l; j <= r; j++) v[j] += d;
        resort(lbucket0);
      } else {
        for (int j = l; j < lstart1; j++) v[j] += d;
        for (int j = bstart(rbucket); j <= r; j++) v[j] += d;
        resort(lbucket0);
        resort(rbucket);
      }
    } else {
      int yy;
      scanf("%d", &yy);
      long long y = yy;
      vector<pair<long long, int> >::iterator it;
      int l = 0, r = -1;
      for (int i = 0; i <= buckets; i++) {
        if (y - offset[i] <= 0) continue;
        pair<long long, int> search = {y - offset[i], 0};
        it = lower_bound(x[i].begin(), x[i].end(), search);
        if (it == x[i].end()) continue;
        if (it->first == y - offset[i]) {
          l = it->second;
          break;
        }
      }
      for (int i = buckets; i >= 0; i--) {
        if (y - offset[i] <= 0) continue;
        pair<long long, int> search = {y - offset[i] + 1, 0};
        it = lower_bound(x[i].begin(), x[i].end(), search);
        if (it == x[i].begin()) continue;
        it--;
        if (it->first == y - offset[i]) {
          r = it->second;
          break;
        }
      }
      printf("%d\n", r - l);
    }
  }
  return 0;
}
