#pragma GCC target("avx2") #pragma GCC optimize("unroll-loops") #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #include #define ALL(x) (x).begin(), (x).end() #define PC(x) __builtin_popcount(x) #define PCL(x) __builtin_popcountll(x) using namespace std; typedef long long ll; typedef unsigned long long ull; typedef pair pii; typedef pair pll; struct edge { int to, cost, id; }; const double PI = 3.14159265358979323846; const double PI2 = PI * 2.0; const double EPS = 1E-09; const ll MOD = 1E+09 + 7; // =998244353; const ll INFL = 1E18; const int INFI = 1E09; const int MAX_N = 1E+06; ll dx[4] = { -1, 1, 0, 0 }, dy[4] = { 0, 0, -1, 1 }; int N, M; string S[MAX_N + 1]; bool solve(string t0, string t1, string& s0f, string& s0b) { string m0 = t0.substr(1); string m1 = t1.substr(0, t1.size() - 1); if (m0 != m1) { return false; } string t = s0f + t0 + m1.back() + s0b; for (int i = 2; i < N; ++i) { if (t.find(S[i]) == string::npos) return false; } return true; } int main() { ios::sync_with_stdio(false); cin.tie(nullptr); cin >> N >> M; for (int i = 0; i < N; ++i) { cin >> S[i]; } int l = -1; while (S[0][l + 1] == S[1][l + 1]) { ++l; } int r = N; while (S[0][r - 1] == S[1][r - 1]) { --r; } string t0 = S[0].substr(l + 1, r - l - 1); string t1 = S[1].substr(l + 1, r - l - 1); int ans = 0; { string s0f = S[0].substr(0, l + 1); string s0b = S[0].substr(r); ans += solve(t0, t1, s0f, s0b); } { string s0f = S[1].substr(0, l + 1); string s0b = S[1].substr(r); ans += solve(t1, t0, s0f, s0b); } // for (int i = 0; i < N; i++) { // for (int j = 0; j < N; j++) { // cout << "i = " << i << ", j = " << j << ", dp = " << dp[i][j] << "\n"; // } // } cout << ans << "\n"; return 0; }