1 #include<cstdio>

 2 #include<algorithm>

 3 #include<cstring>

 4 #include<cmath>

 5 #include<string>

 6 #include<iostream>

 7 using namespace std;

 8 const int maxn=2010;

 9 int n,m,dp[maxn][maxn],w[30];

10 char s[maxn];

11

12 int main(){

13     scanf("%d%d",&n,&m);

14     scanf("%s",s);

15     for(int i=1;i<=n;i++){

16         char c;

17         int k1,k2;

18         cin>>c>>k1>>k2;

19         w[c-'a']=min(k1,k2);//添加和删去效果等价，取最小的

20     }

21     for(int i=m-1;i>=0;i--){

22         for(int j=i+1;j<m;j++){//枚举区间左右端点

23             if(s[i]==s[j]) dp[i][j]=dp[i+1][j-1];

24             else dp[i][j]=min(dp[i+1][j]+w[s[i]-'a'],dp[i][j-1]+w[s[j]-'a']);

25         }

26     }

27     printf("%d",dp[0][m-1]);

28     return 0;

29 }