Codeforces Educational Codeforces Round 3 B. The Best Gift（签到）

//
//  Created by TaoSama on 2015-12-19
//  Copyright (c) 2015 TaoSama. All rights reserved.
//
//#pragma comment(linker, "/STACK:1024000000,1024000000")
#include <algorithm>
#include <cctype>
#include <cmath>
#include <cstdio>
#include <cstdlib>
#include <cstring>
#include <iomanip>
#include <iostream>
#include <map>
#include <queue>
#include <string>
#include <set>
#include <vector>

using namespace std;
#define pr(x) cout << #x << " = " << x << "  "
#define prln(x) cout << #x << " = " << x << endl
const int N = 1e5 + 10, INF = 0x3f3f3f3f, MOD = 1e9 + 7;

typedef long long LL;
LL n, m, cnt[15];

int main() {
#ifdef LOCAL
freopen("C:\\Users\\TaoSama\\Desktop\\in.txt", "r", stdin);
//  freopen("C:\\Users\\TaoSama\\Desktop\\out.txt","w",stdout);
#endif
ios_base::sync_with_stdio(0);

while(scanf("%d%d", &n, &m) == 2) {
memset(cnt, 0, sizeof cnt);
for(int i = 1; i <= n; ++i) {
int x; scanf("%d", &x);
++cnt[x];
}
LL ans = n * (n - 1) >> 1;
for(int i = 1; i <= m; ++i)
ans -= cnt[i] * (cnt[i] - 1) >> 1;
printf("%I64d\n", ans);
}
return 0;
}