class Solution {
    
    
public:
    static int cmp(vector<int> a, vector<int> b)
    {
    
    
        return a[1] > b[1];
    }

    int maximumUnits(vector<vector<int>>& boxTypes, int truckSize) {
    
    
        sort(boxTypes.begin(), boxTypes.end(), cmp);

        int cnt = 0;
        
        for (auto b : boxTypes)
        {
    
    
            if (truckSize >= b[0])
            {
    
    
                cnt += b[1] * b[0];
                truckSize -= b[0];
            }
            else
            {
    
    
                cnt += truckSize * b[1];
                break;
            }
        }
        return cnt;
    }
};