Problem EL: 1 +2 +3……+n>m

Problem EL: 1 +2 +3……+n>m

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Time Limit : 1.000 sec  Memory Limit : 128 MB

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Solved: 150Submit Num: 263Statistics

Description

给定正整数m，求当加到第几项时，s=1 +2 +3……+n的值会首次超过m？

Input

一个整数m

Output

满足条件的n

Sample Input Copy 

10

Sample Output Copy 

5
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