@@ -0,0 +1,17 @@
+#include<iostream>
+using namespace std;
+
+int main()
+{
+ int n;
+ while (cin >> n)
+ {
+ int sum = 0;
+ for (int i = 1; i <= n; i++) {
+ sum += i;
+ }
+ cout << sum << endl << endl;
+ return 0;
+}
