#include <iostream>
#include <climits>
#include <vector>
#include <algorithm>

using namespace std;

bool mycompare(int a, int b) {
	return a>b;
}

int main() {

	int t;
	cin >> t;
	while(t--) {
		int k,n;
		cin >> k >> n;

		int arr[n];
		for(int i=0; i<n; i++) 
			cin >> arr[i];

		int local_min = 0, local_max = 0;
		int ptr=0;
		vector<int> trans;
		while(ptr<(n-1)) {
			//local minima
			while( ptr<(n-1) && arr[ptr]>arr[ptr+1])
				ptr++;
			if(ptr == (n-1)){
				local_min = -1;
				break;
			}

			local_min = ptr;

			//local max
			while( ptr<(n-1) && arr[ptr]<arr[ptr+1])
				ptr++;

			local_max = ptr;
			int tran = arr[local_max]-arr[local_min];
			trans.push_back(tran);
		}

		if(trans.size() <= k){
			int ans = 0;
			for(int i=0; i<trans.size(); i++){
				ans += trans[i];
			}
			cout << ans << endl;
		}else {
			int ans=0;
			sort(trans.begin(), trans.end(), mycompare);
			for(int i=0; i<k; i++) {
				ans += trans[i];
			}
			cout << ans << endl;
		}

	}

	return 0;
}