#include <bits/stdc++.h>
using namespace std;
const int inf = 1000000001;
map<int, int> M1[1000], M2[1000], M3[1000];
int b[1000000], g[1000000], h[1000], v[1000];
int i, j, m, n, q, t, x, y, z, l, r;
int main() {
  scanf("%d%d", &n, &m);
  q = ceil(sqrt(n));
  for (i = 1; i <= n; i++) {
    b[i] = (i - 1) / q + 1;
    v[b[i]]++;
  }
  for (i = 1; i <= n; i++) {
    scanf("%d", &g[i]);
    if (!M1[b[i]].count(g[i])) M2[b[i]][g[i]] = i;
    M1[b[i]][g[i]]++;
    M3[b[i]][g[i]] = i;
  }
  for (i = 1; i <= m; i++) {
    scanf("%d", &t);
    if (t == 1) {
      scanf("%d%d%d", &x, &y, &z);
      if (b[x] == b[y]) {
        M1[b[x]].clear();
        M2[b[x]].clear();
        M3[b[x]].clear();
        for (j = x; j <= y; j++) {
          g[j] = g[j] + z;
          if (g[j] > inf) g[j] = inf;
        }
        for (j = (b[x] - 1) * q + 1; j <= (b[x] - 1) * q + v[b[x]]; j++) {
          if (!M1[b[j]].count(g[j])) M2[b[j]][g[j]] = j;
          M1[b[j]][g[j]]++;
          M3[b[j]][g[j]] = j;
        }
      } else {
        M1[b[x]].clear();
        M2[b[x]].clear();
        M3[b[x]].clear();
        for (j = x; j <= (b[x] - 1) * q + v[b[x]]; j++) {
          g[j] = g[j] + z;
          if (g[j] > inf) g[j] = inf;
        }
        for (j = (b[x] - 1) * q + 1; j <= (b[x] - 1) * q + v[b[x]]; j++) {
          if (!M1[b[j]].count(g[j])) M2[b[j]][g[j]] = j;
          M1[b[j]][g[j]]++;
          M3[b[j]][g[j]] = j;
        }
        M1[b[y]].clear();
        M2[b[y]].clear();
        M3[b[y]].clear();
        for (j = (b[y] - 1) * q + 1; j <= y; j++) {
          g[j] = g[j] + z;
          if (g[j] > inf) g[j] = inf;
        }
        for (j = (b[y] - 1) * q + 1; j <= (b[y] - 1) * q + v[b[y]]; j++) {
          if (!M1[b[j]].count(g[j])) M2[b[j]][g[j]] = j;
          M1[b[j]][g[j]]++;
          M3[b[j]][g[j]] = j;
        }
        for (j = b[x] + 1; j <= b[y] - 1; j++) {
          h[j] = h[j] + z;
          if (h[j] > inf) h[j] = inf;
        }
      }
    } else {
      scanf("%d", &x);
      l = 1, r = 0;
      for (j = 1; j <= (n - 1) / q + 1; j++)
        if (M2[j].count(x - h[j])) {
          l = M2[j][x - h[j]];
          break;
        }
      for (j = (n - 1) / q + 1; j > 0; j--)
        if (M3[j].count(x - h[j])) {
          r = M3[j][x - h[j]];
          break;
        }
      printf("%d\n", r - l);
    }
  }
  return 0;
}
