ROMAN

//
// Created by Роман Климовицкий on 2018-11-27.
//

#include <iostream>
#include <cmath>
#include <string>
#include <vector>


std::string prefixFunction(const std::string& s) {
    int len = s.size();
    std::vector<int> p(len);
    p[0] = 0;
    for (int i = 1; i < len; ++i) {
        int j = p[i - 1];
        while (j > 0 && s[j] != s[i]) {
            j = p[j - 1];
        }
        if (s[j] == s[i]) {
            p[i] = j + 1;
        } else {
            p[i] = 0;
        }
    }
    return s.substr(0, len - p[len - 1]);
}


std::vector<int> zFunction(const std::string& s) {
    int len = s.size();
    std::vector<int> z(len);
    z[0] = len;
    int l = 0;
    int r = 0;
    for (int i = 1; i < len; ++i) {
        if (i > r) {
            z[i] = 0;
        } else {
            z[i] = std::min(r - i + 1, z[i - l]);
        }
        while (i + z[i] < len && s[z[i]] == s[i + z[i]])
            ++z[i];
        if (i + z[i] - 1 > r) {
            l = i;
            r = i + z[i] - 1;
        }
    }
    return z;
}


int main() {
    std::ios::sync_with_stdio(false);
    std::cin.tie(NULL);

    std::string s1, s2;
    std::cin >> s1 >> s2;
    int len1 = s1.size();
    int len2 = s2.size();
    std::string bigS = s2 + static_cast<char>(32) + s1;
    std::string ans = bigS;
    std::string tmpS = s1 + s2;

    tmpS = prefixFunction(s1 + s2);
    if (tmpS.size() < ans.size()) {
        ans.swap(tmpS);
        if (ans.size() <= 2) {
            std::cout << ans << std::endl;
            return 0;
        }
    }

    std::vector<int> bigZF(len1 + len2 + 1);
    bigZF[0] = len1 + len2 + 1;
    int l = 0;
    int r = 0;
    for (int i = 1; i < len1 + len2 + 1; ++i) {
        if (i > r) {
            bigZF[i] = 0;
        } else {
            bigZF[i] = std::min(r - i + 1, bigZF[i - l]);
        }
        while (i + bigZF[i] < len1 + len2 + 1 && bigS[bigZF[i]] == bigS[i + bigZF[i]])
            ++bigZF[i];
        if (i + bigZF[i] - 1 > r) {
            l = i;
            r = i + bigZF[i] - 1;
        }
    }
    for (int i = 1; i <= len1; ++i) {
        if (bigZF[i + len2] == len2) {
            tmpS = prefixFunction(s1);
            if (tmpS.size() <= ans.size()) {
                std::cout << tmpS << std::endl;
                return 0;
            }
        }
        if (i + bigZF[i + len2] - 1 == len1) {
            tmpS = prefixFunction(s1 + s2.substr(bigZF[i + len2], len2 - bigZF[i + len2]));
            if (tmpS.size() < ans.size()) {
                ans.swap(tmpS);
                if (ans.size() <= 2) {
                    std::cout << ans << std::endl;
                    return 0;
                }
            }
        }
    }

    s1.swap(s2);

    len1 = s1.size();
    len2 = s2.size();
    bigS = s2 + static_cast<char>(32) + s1;
    ans = bigS;
    tmpS = s1 + s2;

    tmpS = prefixFunction(s1 + s2);
    if (tmpS.size() < ans.size()) {
        ans.swap(tmpS);
        if (ans.size() <= 2) {
            std::cout << ans << std::endl;
            return 0;
        }
    }

    bigZF[0] = len1 + len2 + 1;
    l = 0;
    r = 0;
    for (int i = 1; i < len1 + len2 + 1; ++i) {
        if (i > r) {
            bigZF[i] = 0;
        } else {
            bigZF[i] = std::min(r - i + 1, bigZF[i - l]);
        }
        while (i + bigZF[i] < len1 + len2 + 1 && bigS[bigZF[i]] == bigS[i + bigZF[i]])
            ++bigZF[i];
        if (i + bigZF[i] - 1 > r) {
            l = i;
            r = i + bigZF[i] - 1;
        }
    }
    for (int i = 1; i <= len1; ++i) {
        if (bigZF[i + len2] == len2) {
            tmpS = prefixFunction(s1);
            if (tmpS.size() <= ans.size()) {
                std::cout << tmpS << std::endl;
                return 0;
            }
        }
        if (i + bigZF[i + len2] - 1 == len1) {
            tmpS = prefixFunction(s1 + s2.substr(bigZF[i + len2], len2 - bigZF[i + len2]));
            if (tmpS.size() < ans.size()) {
                ans.swap(tmpS);
                if (ans.size() <= 2) {
                    std::cout << ans << std::endl;
                    return 0;
                }
            }
        }
    }

    std::cout << ans << std::endl;


    return 0;
}