import std;

void main() {
    int T;
    readf("%d\n", T);

    foreach (_; 0 .. T) {
        int N, M;
        readf("%d %d\n", N, M);

        auto A = [M] ~ readln.chomp.split.to!(int[]);

        bool isOK = true;
        foreach (i; 2 .. N) {
            int d = A[i-2] - A[i-1];
            isOK &= A[i] >= d;
        }

        writeln(isOK ? "Yes" : "No");
    }
}