样例已过，WA 了

#include<bits/stdc++.h>
#define int long long
using namespace std;
int n,m,a[500005],b[500005],t[500005];
int lowbit(int x){
	return x&(-x);
}
int gcd(int a,int b){
	if(b==0)return abs(a);
	return gcd(b,a%b);
}
void change(int x,int k){
	while(x<=n){
		t[x]+=k;
		x+=lowbit(x);
	}
}
int query(int x){
	int res=0;
	while(x){
		res+=t[x];
		x-=lowbit(x);
	}
	return res;
}
struct node{
	int l,r,gcd;
}tree[2000005];
void build(int x,int l,int r){
	tree[x].l=l;
	tree[x].r=r;
	if(l==r){
		tree[x].gcd=b[l];
		return;
	}
	int mid=l+r>>1;
	build(x<<1,l,mid);
	build(x<<1|1,mid+1,r);
	tree[x].gcd=gcd(tree[x<<1].gcd,tree[x<<1|1].gcd);
}
void update(int x,int m,int k){
	if(tree[x].l==tree[x].r){
		tree[x].gcd+=k;
		return;
	}
	int mid=tree[x].l+tree[x].r>>1;
	if(m<=mid)update(x<<1,m,k);
	else update(x<<1|1,m,k);
	tree[x].gcd=gcd(tree[x<<1].gcd,tree[x<<1|1].gcd);
}
int ask(int x,int l,int r){
	if(l<=tree[x].l&&tree[x].r<=r)return tree[x].gcd;
	int mid=tree[x].l+tree[x].r>>1,ans=0;
	if(l<=mid)ans=gcd(ans,ask(x<<1,l,mid));
	if(mid+1<=r)ans=gcd(ans,ask(x<<1|1,mid+1,r));
	return ans;
}
signed main(){
	cin>>n>>m;
	for(int i=1;i<=n;i++){
		cin>>a[i];
		b[i]=a[i]-a[i-1];
		change(i,b[i]);
	}
	build(1,1,n);
	while(m--){
		char id;
		cin>>id;
		if(id=='C'){
			int l,r,d;
			cin>>l>>r>>d;
			change(l,d);
			change(r+1,-d);
			update(1,l,d);
			if(r+1<=n)update(1,r+1,-d);
		}
		else{
			int l,r;
			cin>>l>>r;
			cout<<gcd((l+1<=r?ask(1,l+1,r):0),query(l))<<'\n';
		}
	}
	return 0;
}