#include <fstream>

using namespace std;
ifstream fin("nrcuv.in");
ofstream fout("nrcuv.out");
bool a[28][28];
int i,j,q,n,m,b[28][1001],s;
char x,y;
int main()
{
    fin>>n>>m;
    for(i=1;i<=m;i++)
    {
    	fin>>x>>y;
    	a[x-'a'+1][y-'a'+1]=1;
    }
    for(i=1;i<='z'-'a'+1;i++)
		b[1][i]=1;
	for(q=2;q<=n;q++)
	{
		for(i=1;i<='z'-'a'+1;i++)
		for(j=1;j<='z'-'a'+1;j++)
		if(a[i][j]==0)
			b[q][i]=b[q][i]+b[q-1][j];
	}
	for(i=1;i<='z'-'a'+1;i++)
		s=s+b[n][i];
	fout<<s;
    return 0;
}