#include<cstring>

 #include<cstdlib>

 #include<cstdio>

 //#include<assert.h>

 //#include<time.h>

 #include<math.h>

 #include<algorithm>

 //#include<iostream>

 using namespace std;

 bool isdigit(char c) {return c>='' && c<='';}

 int qread()

 {

     char c;int s=,f=;while (!isdigit(c=getchar())) f=(c=='-'?-:);

     do s=s*+c-''; while (isdigit(c=getchar())); return s*f;

 }

 const int mod=;

 int da,xiao,m;

 int f[][][];

 int id(char c) {return (c>='a' && c<='z')?c-'a':c-'A'+;}

 bool isalpha(char c) {return (c>='a' && c<='z') || (c>='A' && c<='Z');}

 struct Edge{int to,next;}edge[];int first[],le=;

 void in(int x,int y) {Edge &e=edge[le];e.to=y;e.next=first[x];first[x]=le++;}

 int main()

 {

     da=qread(),xiao=qread(),m=qread();

     memset(first,,sizeof(first));

     for (int i=;i<=m;i++)

     {

         char c1,c2;

         while (!isalpha(c1=getchar()));

         c2=getchar();

         in(id(c2),id(c1));

     }

     for (int i=;i<;i++) f[][][i]=,f[][][i]=;

     for (int i=;i<;i++) f[][][i]=,f[][][i]=;

     for (int i=;i<=da;i++)

         for (int j=;j<=xiao;j++) if (i+j>=)

         {

             if (j) for (int now=;now<;now++)

             {

                 f[i][j][now]=;

                 for (int k=first[now];k;k=edge[k].next)

                 {

                     const Edge &e=edge[k];

                     f[i][j][now]+=f[i][j-][e.to],

                     f[i][j][now]-=f[i][j][now]>=mod?mod:;

                 }

             }

             if (i) for (int now=;now<;now++)

             {

                 f[i][j][now]=;

                 for (int k=first[now];k;k=edge[k].next)

                 {

                     const Edge &e=edge[k];

                     f[i][j][now]+=f[i-][j][e.to],

                     f[i][j][now]-=f[i][j][now]>=mod?mod:;

                 }

             }

         }

     int ans=;

     for (int i=;i<;i++) ans+=f[da][xiao][i],ans-=ans>=mod?mod:;

     printf("%d\n",ans);

     return ;

 }