22173_RebuildTheGreatWa

In 1368 A.D., in China, the king Yuanzhang Zhu won the war and build up the Ming dynasty, we've talked about that before. To resist Mongolian army, the King decided to rebuild the Great Wall. However, the Kingdom spent quite a lot of money on the project before (If you are confuse, please check out the former problem! ^_^), they can only rebuild part of the Great Wall.

There're many segments of Great Wall from west to east. For every segment, there's an integer number as resistant value. Now, the kingdom wants to continuously rebuild minimum segments that the sum of resistant value is greater than T.

There're several groups of data.

For each group, the first line of Input contains two integer N ( N ≤ 100000 ) and T ( T ≤ 2*10⁹ ). N means the number of segments of Great Wall, T was defined in background.

And then N integers in one line present the resistant value of every segment from west to east.

Output one integer as the minimum number of continuously segments in one line.

If there's no solution, print out -1 in one line.

7 18
5 8 4 9 10 5 2

2
2