#include <iostream>

 #include <cstdio>

 #include <cstring>

 using namespace std;

 #define Dollar1 998244353

 #define MAXN 70001

 #define int long long

 int lim, dig, rev[MAXN], n, sums[MAXN], A[MAXN];

 const int G = , Ginv = (Dollar1 + ) / ;

 void init(int sz) {

     lim = ; dig = ;

     while (lim <= sz << ) lim <<= , ++dig;

     for (int i = ; i != lim; ++i)

         rev[i] = (rev[i >> ] >> ) | ((i & ) << (dig - ));

 }

 inline int fastpow(int a, int b) {

     int res = ;

     while (b) {

         if (b & ) res = res * a % Dollar1;

         a = a * a % Dollar1;

         b >>= ;

     }

     return res;

 }

 void NTT(int * A, int type) {

     for (int i = ; i != lim; ++i)

         if (i < rev[i])

             swap(A[i], A[rev[i]]);

     for (int mid = ; mid < lim; mid <<= ) {

         int Wn = fastpow(type ==  ? G : Ginv, (Dollar1 + ) / mid / );

         for (int k = ; k < lim; k += (mid << )) {

             int W = ;

             for (int l = ; l < mid; ++l, W = W * Wn % Dollar1) {

                 int X = A[l + k], Y = A[l + k + mid] * W % Dollar1;

                 A[l + k] = (X + Y) % Dollar1;

                 A[l + k + mid] = (X - Y + Dollar1) % Dollar1;

             }

         }

     }

     if (type == -) {

         const int liminv = fastpow(lim, Dollar1 - );

         for (int i = ; i != lim; ++i)

             A[i] = A[i] * liminv % Dollar1;

     }

 }

 signed main() {

     cin >> n;

     init();

     for (int i = ; i <= n; ++i) cin >> sums[i], A[sums[i]] = ;

     NTT(A, );

     for (int i = ; i != lim; ++i) (A[i] *= A[i]) %= Dollar1;

     NTT(A, -);

     for (int i = ; i <= n; ++i) --A[sums[i] << ];

     int ans = ;

     for (int i = ; i <= n; ++i) ans += (bool)A[sums[i]];

     cout << ans << endl;

     return ;

 }