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  1. #include <iostream>
  2. #include <math.h>
  3.  
  4. using namespace std;
  5.  
  6. long long n, m;
  7.  
  8. int main(){
  9. 	cin >> n >> m;
  10. 	//long long k = d= 1;
  11. 	if (m >= n) cout << n;
  12. 	else{
  13. 		long long k = (-1.0+(sqrt(8*(n-m))))/2.0;
  14. 		if ((k*(k+1)/2 + m)>=n) cout << k+m;
  15. 		else cout << k+m+1;
  16. 	}
  17. 	return 0;
  18. }
Success #stdin #stdout 0s 15240KB
comments (?)
stdin 
999999998765257151 10
stdout 
1414213571
https://ideone.com/1GjQch
language:
C++ (gcc 8.3)
created:
9 years ago
visibility:
public

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