/*
TASK:balls
LANG:C++
*/
#include<iostream>
#include<string.h>
using namespace std;
char a[1000],b[1000];
int q[7],p[7],br,n,m;
void vhod()
{int i,j;
 cin>>a>>b;
 n=strlen(a);
 m=strlen(b);
 for(i=0;i<n;i++)
  {if(a[i]=='b'){a[i]=1;p[1]++;}
   else if(a[i]=='g'){a[i]=2;p[2]++;}
   else if(a[i]=='p'){a[i]=3;p[3]++;}
   else if(a[i]=='r'){a[i]=4;p[4]++;}
   else if(a[i]=='w'){a[i]=5;p[5]++;}
   else if(a[i]=='y'){a[i]=6;p[6]++;}
  }
 for(i=0;i<m;i++)
  {if(b[i]=='b'){b[i]=1;q[1]++;}
   else if(b[i]=='g'){b[i]=2;q[2]++;}
   else if(b[i]=='p'){b[i]=3;q[3]++;}
   else if(b[i]=='r'){b[i]=4;q[4]++;}
   else if(b[i]=='w'){b[i]=5;q[5]++;}
   else if(b[i]=='y'){b[i]=6;q[6]++;}
  }
 for(i=1;i<=6;i++)
  { if(p[i]>q[i])br+=q[i];
     else if(p[i]<q[i])br+=p[i];
     else br+=q[i];
  }
 cout<<br-1<<endl;
}
int main()
{
 vhod();
 return 0;
}

