#include <iostream>
#include <vector>
using namespace std;
vector<int> ucs(vector<int> A, vector<int> B) {
int N = A.size(), M = B.size();
vector<vector<int>> dp(N + 1, vector<int>(M + 1, 0));
vector<vector<bool>> unique(N + 1, vector<bool>(M + 1, true));
// Fill dp table
for (int i = N - 1; i >= 0; --i) {
for (int j = M - 1; j >= 0; --j) {
if (A[i] == B[j]) {
dp[i][j] = 1 + dp[i + 1][j + 1];
unique[i][j] = unique[i + 1][j + 1];
} else {
if (dp[i + 1][j] > dp[i][j + 1]) {
dp[i][j] = dp[i + 1][j];
unique[i][j] = unique[i + 1][j];
} else if (dp[i + 1][j] < dp[i][j + 1]) {
dp[i][j] = dp[i][j + 1];
unique[i][j] = unique[i][j + 1];
} else {
dp[i][j] = dp[i + 1][j]; // same as dp[i][j+1]
unique[i][j] = false; // two equal options → not unique
}
}
}
}
if (!unique[0][0]) return {-1}; // multiple UCS paths
// Reconstruct UCS
vector<int> lcs;
int i = 0, j = 0;
while (i < N && j < M) {
if (A[i] == B[j]) {
lcs.push_back(A[i]);
++i;
++j;
} else if (dp[i + 1][j] > dp[i][j + 1]) {
++i;
} else {
++j;
}
}
return lcs;
}
