include[HTML_REMOVED]
using namespace std;
const int N=1e6+10;
string s;
int main()
{
int n;
char a,b;
cin>>n;
cin>>s;
cin>>a>>b;
int t=s.size();
int m=0;
int i=0,j=0;
while(i<=t-n+2)
{
if(s[i]==a)
{
j=i+n-1;
while(j<=t)
{
if(s[j]==b)
{
m;
}
j;
}
}
i++;
}
cout<<m;
return 0;
}