#include<stdio.h>
#include<iostream>
#include<algorithm>
#include<string.h>
#include<math.h>
#include<queue>
#include<string>
#include<stack>
#include<map>
#define pf printf
#define pfn printf("\n");
#define wsa while(~scanf("%d",&a))
#define forba for(b=0;b<a;b++)
#define st scanf("%d",&t);
#define wt while(t--)
#define scdx scanf("%d",&x[b]);
#define sclldx scanf("%lld",&x[b]);
#define inf 0x3f3f3f3f;
using namespace std;
int main()
{
    int a,b,c,d,e,f,g;
    map<int,long long> mp;
    cin>>a;
    forba
    {
        cin>>c;
        mp[c%200]++;
    }
    long long sum;
    sum=0;
    for(auto x:mp)
    {
        sum+=x.second*(x.second-1)/2;
    }
    cout<<sum;
}

#include <algorithm>
#include <bitset>
#include <cmath>
#include <complex>
#include <cstdio>
#include <iostream>
#include <map>
#include <numeric>
#include <queue>
#include <set>
#include <stack>
#include <string>
#include <sys/types.h>
#include <unistd.h>
#include <vector>

#pragma region macros
#define _overload(_1, _2, _3, name, ...) name
#define _rep(i, n) _range(i, 0, n)
#define _range(i, a, b) for (int i = int(a); i < int(b); ++i)
#define rep(...) _overload(__VA_ARGS__, _range, _rep, )(__VA_ARGS__)
#define _rrep(i, n) _rrange(i, n, 0)
#define _rrange(i, a, b) for (int i = int(a) - 1; i >= int(b); --i)
#define rrep(...) _overload(__VA_ARGS__, _rrange, _rrep, )(__VA_ARGS__)
#pragma endregion macros

using namespace std;

template <class T> bool chmax(T &a, const T &b) {
    return (a < b) ? (a = b, 1) : 0;
}
template <class T> bool chmin(T &a, const T &b) {
    return (b < a) ? (a = b, 1) : 0;
}

using ll    = long long;
using R     = long double;
const R EPS = 1e-9L;  // [-1000,1000]->EPS=1e-8 [-10000,10000]->EPS=1e-7
inline int sgn(const R &r) {
    return (r > EPS) - (r < -EPS);
}
inline R sq(R x) {
    return sqrt(max(x, 0.0L));
}

const int dx[8] = {1, 0, -1, 0, 1, -1, -1, 1};
const int dy[8] = {0, 1, 0, -1, 1, 1, -1, -1};

const pid_t pid = getpid();
// Problem Specific Parameter:

int main(void) {
    int n;
    cin >> n;
    vector<int> a(n);

    vector<int> cnt(200, 0);

    rep(i, n) {
        cin >> a[i];
        a[i] %= 200;
        cnt[a[i]]++;
    }

    ll ans = 0LL;
    rep(i, 200) {
        const int k = cnt[i];
        ans += 1LL * k * (k - 1) / 2LL;
    }

    cout << ans << endl;

    return 0;
}