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  1. #include <iostream>
  2. using namespace std;
  3.  
  4. int to_digit(int num) {
  5. 	if (num / 10 == 0) {
  6. 		return num;
  7. 	}
  8.  
  9. 	return to_digit(num / 10 + num % 10);
  10. }
  11.  
  12. int main() {
  13. 	cin.tie(0);
  14. 	ios::sync_with_stdio(false);
  15.  
  16. 	int a, b;
  17. 	long long res = 0;
  18.  
  19. 	cin >> a >> b;
  20.  
  21. 	for (int i = a; i <= b; i++) {
  22. 		res += to_digit(i / 9 + i % 9);
  23. 	}
  24.  
  25. 	cout << res;
  26.  
  27. 	return 0;
  28. }
Success #stdin #stdout 0s 5316KB
comments (?)
stdin 
10 20
stdout 
53
https://ideone.com/Nnc5t5
language:
C++ (gcc 8.3)
created:
38 minutes ago
visibility:
public

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