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  1. #include <bits/stdc++.h>
  2.  
  3. #define pb push_back
  4.  
  5. using namespace std;
  6.  
  7. int main() { 
  8. 	long long l, r;
  9. 	cin >> l >> r;
  10. 	long long sum = 0;
  11. 	long long m = 1e9 + 7;
  12. 	if (r % 2 == 0) {
  13. 		sum = (r / 2) % m * (r / 2) % m + (r / 2) % m * (r / 2) % m + (r / 2) % m - (l / 2) % m * (l / 2) % m + (l / 2) % m * (l / 2) % m + (l / 2) % m;
  14. 		cout << sum;
  15. 	}
  16. 	else {
  17. 		sum = ((r + 1) / 2) % m * ((r + 1) / 2) % m + (r / 2) % m * (r / 2) % m + (r / 2) % m  - ((l+1) / 2) % m * ((l+1) / 2) % m + ((l+1) / 2) % m * ((l+1) / 2) % m + ((l+1) / 2) % m;
  18. 		cout << sum;
  19. 	}
  20. 	return 0; 
  21. }
Success #stdin #stdout 0s 15232KB
comments (?)
stdin
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88005553535 99999999999
stdout
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-491042217
https://ideone.com/KgfHyo
language:
C++14 (gcc 8.3)
created:
5 years ago
visibility:
public

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