1 #include <bits/stdc++.h> 2 using namespace std; 3  4 const int maxn = 50500; 5 char s[maxn], t[maxn]; 6 int n; 7 map<string, int> ok; 8  9 int main() {10   //freopen("in", "r", stdin);11   while(~scanf("%d", &n)) {12     ok.clear();13     for(int i = 0; i < n; i++) {14       scanf("%s", s);15       int n = strlen(s);16       memset(t, 0, sizeof(t));17       for(int j = n - 1; j >= 0; j--) t[n-j-1] = s[j];18       ok[s]++; ok[t]++;19     }20     int ret = 0;;21     for(auto it : ok) if(it.second != 1) ret++;22     printf("%d\n", ret/2);23   }24   return 0;25 }