#include<iostream.h>
#include<string.h>
 void main()
   { char a[100],b[100];
    int i,j;
    cin>>a>>b;
    i=strlen(a)-1;
    j=strlen(b)-1;
     while(a[i]==b[j]) { i--;
			 j--;
			}
   cout<<a+i+1;
   }