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28 lines
524 B
C#
28 lines
524 B
C#
using System;
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namespace problem_609A
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{
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class problem_609A
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{
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public static void Main(string[] args)
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{
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int[] ip = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
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int[] a = new int[ip[1]];
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int[] b = Array.ConvertAll(Console.ReadLine().Split(), int.Parse);
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for (int i = 0; i < ip[0]; i++)
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{
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a[b[i] - 1]++;
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}
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long op = 0;
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for (int i = 0; i < ip[1] - 1; i++)
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{
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for (int j = i + 1; j < ip[1]; j++)
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{
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op += a[i] * a[j];
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}
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}
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Console.Write("{0}", op);
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}
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}
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}
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