#include<iostream>
#include<map>
#include<algorithm>
#include<cstdio>
#include<cstring>
#include<cstdlib>
#include<vector>
#include<queue>
#include<stack>
#include<functional>
#define pb push_back
using namespace std;
typedef long long ll;
const int maxv=5e5+40;
const int sz=1000;
struct Num{ll o,v;bool operator < (const Num &C)const{if(v!=C.v) return v<C.v;else return o<C.o;}
};
vector<Num> bucket[1000];
ll a[maxv];
ll val[maxv];
int n,q;
void update(int l,int r,ll x){if(l/sz==r/sz){for(int i=l;i<=r;i++) a[i]+=x;bucket[l/sz].clear();for(int i=l/sz*sz;i<l/sz*sz+sz;i++) bucket[l/sz].pb((Num){i,a[i]});sort(bucket[l/sz].begin(),bucket[l/sz].end());}else{for(int i=l/sz+1;i<r/sz;i++) val[i]+=x;update(l,l/sz*sz+sz-1,x);update(r/sz*sz,r,x);}return;
}
bool cmp(Num a,Num b){return a.v<b.v;
}
int quaryl(ll y){for(int i=0;i<=n/sz;i++){Num tar;tar.v=y-val[i];vector<Num>::iterator it=lower_bound(bucket[i].begin(),bucket[i].end(),tar,cmp);if(it!=bucket[i].end()&&(*it).v==tar.v){return (*it).o;}}return -1;
}
int queryr(ll y){for(int i=n/sz;i>=0;i--){Num tar;tar.v=y-val[i];vector<Num>::iterator it=upper_bound(bucket[i].begin(),bucket[i].end(),tar,cmp);if(it!=bucket[i].begin()&&(*(it-1)).v==tar.v){return (*(it-1)).o;}}return -1;
}
int main(){////freopen("/home/files/CppFiles/in","r",stdin);cin>>n>>q;for(int i=0;i<n;i++){scanf("%I64d",&a[i]);bucket[i/sz].pb((Num){i,a[i]});}for(int i=0;i<=n/sz;i++) sort(bucket[i].begin(),bucket[i].end());while(q--){int type;scanf("%d",&type);if(type==1){int l,r,x;scanf("%d%d%d",&l,&r,&x);update(l-1,r-1,x);}else{int y;scanf("%d",&y);int l=quaryl(y);if(l!=-1){printf("%d\n",queryr(y)-l);}else{puts("-1");}}}return 0;
}