#include#includeusing namespace std;// 比较两个大数字符串 a 和 b,返回 true 如果 a >= b,否则 falsebool isGreaterOrEqual(const string &a, const string &b) {if (a.length() > b.length()) return true;if (a.length() < b.length()) return false;return a >= b;}// 大数减法,假设 a >= b,将字符串 a 减去 b,返回结果string subtractStrings(string a, const string &b) {int carry = 0;for (int i = 0; i < b.length(); i++) {int ai = a[a.length() - 1 - i] - '0';int bi = b[b.length() - 1 - i] - '0';int diff = ai - bi - carry;if (diff < 0) {diff += 10;carry = 1;} else {carry = 0;}a[a.length() - 1 - i] = diff + '0';}for (int i = b.length(); i < a.length(); i++) {int ai = a[a.length() - 1 - i] - '0';if (ai == 0 && carry == 1) {a[a.length() - 1 - i] = '9';} else {a[a.length() - 1 - i] = (ai - carry) + '0';carry = 0;}}// 去除前导零while (a.length() > 1 && a[0] == '0') {a.erase(a.begin());}return a;}// 大数取模函数:将大数字符串 a 对大数字符串 b 取模string modStrings(string a, const string &b) {while (isGreaterOrEqual(a, b)) {a = subtractStrings(a, b);}return a;}// 大数 GCD 函数,使用字符串实现的欧几里得算法string gcdLarge(string a, string b) {while (b != "0") {string temp = modStrings(a, b);a = b;b = temp;}return a;}int main() {string a, b;cin >> a >> b;cout << gcdLarge(a, b) << endl; // 输出大数 GCDreturn 0;}