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#include <bits/stdc++.h>
using namespace std;

#define int long long int

int maxSubarraySum(vector<int> &arr) {
    int res = arr[0];
    int maxEnding = arr[0];

    for (int i = 1; i < arr.size(); i++) {
        maxEnding = max(maxEnding + arr[i], arr[i]);
        res = max(res, maxEnding);
    }
    return res;
}

int32_t main() {
    
     int x;
     cin>>x;
	   
	 int n;
	 cin>>n;
	 
	 vector<int> arr(n);
	 int sum =0;
	 for(int i=0;i<n;i++){
	     int x;
	     cin>>x;
	     sum+=x;
	     arr[i]=x;
	 }
	 
	 vector<int> small(n);
	 for(int i=0;i<n;i++){
	     small[i] = arr[i]/x;
	 }
	 
	
	 cout<<max(maxSubarraySum(arr)*x,maxSubarraySum(small))<<endl;
	 
	 
	 

}