/* too fool to solve this problem */ #include <bits/stdc++.h> #include <ext/pb_ds/assoc_container.hpp> #include <ext/pb_ds/tree_policy.hpp> #define all(x) x.begin(), x.end() #define allr(x) x.rbegin(), x.rend() #define ll long long using namespace std; using namespace __gnu_pbds; template<class T> using ordered_set = tree<T, null_type, less<T>, rb_tree_tag, tree_order_statistics_node_update>; template<class T> using ordered_multiset = tree<T, null_type, less_equal<T>, rb_tree_tag, tree_order_statistics_node_update>; const ll INF = LLONG_MAX; const ll N = 2 * 100000 + 5; const ll MOD = 1e9 + 7; ll binpow(ll a,ll b){ ll res = 1; while(b){ if(b & 1){ res *= a; } a *= a; b/=2; } return res; } void dumb_ass() { ll n,d; cin >> n >> d; vector<string> a(n); for(ll i = 0;i < n;i++){ cin >> a[i]; } ll ans = 0; for(ll i = 0;i < n;i++){ for(ll j = i + 1;j < n;j++){ ll cnt = 0; for(ll k = 0;k < 4;k++){ if(a[i][k] != a[j][k]){ cnt++; } } if(cnt == d){ ans++; } } } cout << ans; } int main() { ios_base::sync_with_stdio(false); cin.tie(0);cout.tie(0); //freopen("A.in","r",stdin); //freopen("A.out","w",stdout); dumb_ass(); }