import java.util.*;

public class Solution { /** * * @param x int整型 * @return int整型 */ public int mysqrt (int x) { if(x==0) return 0; if(x<4) return 1; int l = 1, r = x/2; while(l<=r){ int mid = l+(r-l+1)/2; if(mid<=x/mid&& (mid+1)>x/(mid+1)){ return mid;

        }else if(mid > x/mid){
            r = mid-1;
        }else if(mid<x/mid){
            l = mid+1;
        }
   
    }
    return -1;
}

}