/**
knakul853
**/
class Solution {
public:
    bool isPerfectSquare(int num) {

      int l = 0;
      int h = num;
      while(l<=h)
      {
        long long mid = (l+h)/2;
        if(mid*mid==num)return true;
        if(mid*mid>num)
          h = mid-1;
        else
          l = mid+1;
      }
        return false;


    }
};