B

#include <bits/stdc++.h>

using namespace std;

#define ll     long long
#define _test   int _TEST; cin>>_TEST; while(_TEST--)
#define ff     first
#define ss     second
#define pb     push_back

int main()
{
    _test
    {
        int n;
        cin>>n;

        vector<int> a(n), digits;
        for(auto &e: a)
            cin>>e;

        int prev = 0;
        int f = 1;

        for(auto e: a)
        {
            if(e < prev)
            {
                f = 0;
                break;
            }

            digits.clear();
            int tmp = e;

            while(e > 0)
            {
                digits.pb(e%10);
                e /= 10;
            }

            if(!digits.size())      digits.pb(0);

            reverse(digits.begin(), digits.end());

            if(digits.front() < prev)
            {
                prev = tmp;
                continue;
            }

            int chk = 1;

            for(int i=1; i<digits.size(); i++)
            {
                if(digits[i] < digits[i-1])
                {
                    chk = 0;
                    break;
                }
            }

            if(!chk)        prev = tmp;
            else            prev = digits.back();
        }

        if(f)       cout<<"YES\n";
        else        cout<<"NO\n";
    }
}