#include <bits/stdc++.h>
using namespace std;
int inc[500], n, q, a, b, c, d, x;
int arr[500][1000];
map<int, set<short> > pos[500];
set<short>::iterator it;
map<int, bool> flag;
int main() {
  scanf("%d %d", &n, &q);
  for (int f = 0; f < n; f++) {
    scanf("%d", &x);
    arr[f / 1000][f % 1000] = x;
    pos[f / 1000][x].insert(f % 1000);
  }
  for (int f = 0; f < q; f++) {
    scanf("%d", &a);
    if (a == 1) {
      scanf("%d %d %d", &b, &c, &x);
      b--;
      c--;
      while (b % 1000 && b <= c) {
        if (flag[b]) {
          b++;
          continue;
        }
        if (arr[b / 1000][b % 1000] > 1e9) {
          pos[b / 1000].erase(arr[b / 1000][b % 1000]);
          flag[b] = 1;
          b++;
          continue;
        }
        pos[b / 1000][arr[b / 1000][b % 1000]].erase(b % 1000);
        if (pos[b / 1000][arr[b / 1000][b % 1000]].size() == 0)
          pos[b / 1000].erase(arr[b / 1000][b % 1000]);
        pos[b / 1000][arr[b / 1000][b % 1000] + x].insert(b % 1000);
        arr[b / 1000][b % 1000] += x;
        b++;
      }
      while (c - b >= 999) {
        if (inc[b / 1000] > 1e9) {
          b += 1000;
          continue;
        }
        inc[b / 1000] += x;
        b += 1000;
      }
      while (b <= c) {
        if (flag[b]) {
          b++;
          continue;
        }
        if (arr[b / 1000][b % 1000] > 1e9) {
          pos[b / 1000].erase(arr[b / 1000][b % 1000]);
          flag[b] = 1;
          b++;
          continue;
        }
        pos[b / 1000][arr[b / 1000][b % 1000]].erase(b % 1000);
        if (pos[b / 1000][arr[b / 1000][b % 1000]].size() == 0)
          pos[b / 1000].erase(arr[b / 1000][b % 1000]);
        pos[b / 1000][arr[b / 1000][b % 1000] + x].insert(b % 1000);
        arr[b / 1000][b % 1000] += x;
        b++;
      }
    } else {
      scanf("%d", &x);
      int first = -1, last = -2;
      for (int f = 0; f < 500; f++) {
        if (pos[f].find(x - inc[f]) != pos[f].end()) {
          first = *pos[f][x - inc[f]].begin() + f * 1000;
          break;
        }
      }
      for (int f = 499; f >= 0; f--) {
        if (pos[f].find(x - inc[f]) != pos[f].end()) {
          it = pos[f][x - inc[f]].end();
          it--;
          last = *it + f * 1000;
          break;
        }
      }
      printf("%d\n", last - first);
    }
  }
}
