#include <bits/stdc++.h> // solved by bekagg #define int long long #define ent '\n' #define pb push_back #define all(x) x.begin(),x.end() #define PRaim_bek_abi ios_base::sync_with_stdio(0);cin.tie(0); using namespace std; const int N = 1e5+5; const int MOD = 1e9+7; int n , d , ans; map<string , int>mp; vector<char>v; string s[N]; void arkanefury228(){ cin >> n >> d; if (n <= 2000){ for (int i = 1; i <= n; i++){ cin >> s[i]; for (int j = 1; j < i; j++){ int sum = 0; for (int k = 0; k < 4; k++){ if (s[i][k] != s[j][k]) sum++; } if (sum == d) ans++; } } cout << ans; return; } if (d == 0){ for (int i = 1; i <= n; i++){ cin >> s[i]; ans += mp[s[i]]; mp[s[i]]++; } cout << ans; return; } } signed main(){ PRaim_bek_abi int t=1; //cin>>t; for (int respagold = 1; respagold <= t; respagold++) arkanefury228(); }