using System;
public class Test
{
public static void Main(){
int[] M = new int[10] { 1, 2, 3, 4, 5, 6, 7, 8, 9, 10 };
int mul = 1;
int idx = 1;
while (idx < M.Length) {
mul *= M[idx];
idx *= 2;
}
Console.WriteLine(mul);
}
}
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