public:
    int findPlatform(int arr[], int dep[], int n)
    {
         sort ( arr,arr+n);sort ( dep , dep+n);
         int i=0;int j=0;int count=0,maxCount=0;
         while ( i<n&&j<n){
             if ( arr[i]<=dep[j]) 
             {count++;i++;}
             else 
             {count--;j++;}
             maxCount=max(count,maxCount);
         }
         return maxCount;
    }
};