2016. Maximum Difference Between Increasing Elements

class Solution {
public:
    int maximumDifference(vector<int>& a) {
        int N=a.size();
        int m=a[N-1];
        int max=-1;
        
        for(int i=N-2; i>=0; i--){
           
            if(m<=a[i])
               m=a[i];
               
             else if(max<(m-a[i]))
                    max=m-a[i];
            
               
            
        }
        return max; 
    }
};