class Solution {
public:
    int sqrt(int x) {
        if(x <=1)
            return x;
        
        int begin = 1;
        int end = x;
        int middle = 0;
        while(begin <= end){
            middle = begin+(end-begin)/2;
            if(middle ==x/middle)
                return middle;
            else{
                if(middle < x/middle){
                    begin = middle+1;
                }else{
                    end = middle-1;
                }
            }
        }
        if(end*end>x) return end-1;
           return end;
    }
};