func_code_string: #include <bits/stdc++.h>   using namespace std;      #define     F       first   #define     S       second   typedef pair<int, int>  pi;   typedef long long       ll;   const ll big = 1e6 + 9;   ll GCD(ll a,ll b)   {       if(!b)           return a;       return GCD(b, a % b);   }   ll LCM(ll a,ll b)   {       return a*b/GCD(a,b);   }      int main()   {ios_base::sync_with_stdio(0);       cin.tie(0);cout.tie(0);          ll t;       cin >> t;       while(t--)       {           string s, t;           cin >> s >> t;           ll n1 = s.size(), n2 = t.size();           ll lcm = LCM(n1,n2);           ll k1 = lcm/n1, k2 = lcm/n2;           k1--,k2--;              string s1 = s, t1 = t;           while(k1--)               s += s1;           while(k2--)               t += t1;           if(s == t)               cout << s <<   n ;           else               cout <<  -1 n ;       }          return 0;   }