内部比赛 G A Game with Marbles

A Game with Marbles

Time Limit: 1000MS Memory limit:
65536K

题目描述

There
are n bowls, numbered from 1 to n. Initially,
bowl i contains mi marbles. One game step
consists of removing one marble from a bowl. When removing a marble
from bowl i (i > 1), one marble is
added to each of the first i-1 bowls; if a marble is removed
from bowl 1, no new marble is added. The game is finished
after each bowl is empty.Your job is to determine how many game
steps are needed to finish the game. You may assume that the supply
of marbles is sufficient, and each bowl is large enough, so that
each possible game step can be executed.

Input Specification

The input contains several test cases.
Each test case consists of one line containing one integer n
(1 ≤ n ≤ 50), the number of bowls in the game. The following
line contains nintegers mi (1 ≤ i ≤ n,
0 ≤ mi ≤ 1000), where mi gives the
number of marbles in bowl i at the beginning of the
game.The last test case is followed by a line
containing 0.

输入

The
input contains several test cases. Each test case consists of one
line containing one integer n (1 ≤ n ≤ 50), the
number of bowls in the game. The following line contains
nintegers mi (1 ≤ i ≤ n, 0 ≤
mi ≤ 1000), where mi gives the
number of marbles in bowl i at the beginning of the
game.The last test case is followed by a line
containing 0.

输出

For
each test case, print one line with the number of game steps needed
to finish the game. You may assume that this number fits into a
signed 64-bit integer (in C/C++ you can use the data type "long
long", in JAVA the data type "long").

示例输入

示例输出