Problem B: 计算1+2+3+...

Problem B: 计算1+2+3+...

Time Limit: 1 Sec  Memory Limit: 128 MB
Submit: 550  Solved: 462
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Description

输入正整数N（N≤65535），计算1+2+3+...+N，并输出计算结果

Sample Input Copy 

1
2
10
11
100
101
1000

Sample Output Copy 

1
3
55
66
5050
5151
500500
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