#include <bits/stdc++.h>   using namespace std;   int T, n, a[30005], b[30005];   long long sum[2];   int main() {     scanf( %d , &T);     while (T--) {       scanf( %d , &n);       for (int i = 1; i <= n; i++) scanf( %d , &a[i]);       a[n + 1] = 0;       for (int i = 1; i <= n + 1; i++) b[i] = a[i] - a[i - 1];       sum[0] = sum[1] = 0;       for (int i = 2; i <= n; i++) {         if (b[i] > 0)           sum[0] += b[i];         else           sum[1] -= b[i];       }       if (b[1] >= sum[1] && -b[n + 1] >= sum[0]) {         printf( YES n );       } else         printf( NO n );     }     return 0;   }   