Problem B: 求s=1+2+3+4+…+n
Memory Limit:128 MB
Time Limit:1 S
Judge Style:Text Compare
Creator:
Submit:1998
Solved:1444
Description
求s=1+2+3+4+…+n
Input
输入一个正整数n
Output
输出1+2+3+4+…+n的值
Sample Input Copy
3
Sample Output Copy
6