1 #include<cstdio>  2 #include<cstdlib>  3 #include<cmath>  4 #include<cstring>  5 #include<algorithm>  6 #include<iostream>  7 #include<vector>  8 #include<map>  9 #include<set> 10 #include<queue> 11 #include<string> 12 #define inf 1000000000 13 #define maxn 2000+5 14 #define maxm 500+100 15 #define eps 1e-10 16 #define ll long long 17 #define pa pair<int,int> 18 #define for0(i,n) for(int i=0;i<=(n);i++) 19 #define for1(i,n) for(int i=1;i<=(n);i++) 20 #define for2(i,x,y) for(int i=(x);i<=(y);i++) 21 #define for3(i,x,y) for(int i=(x);i>=(y);i--) 22 #define for4(i,x) for(int i=head[x],y;i;i=e[i].next) 23 #define mod 1000000007 24 using namespace std; 25 inline int read() 26 { 27     int x=0,f=1;char ch=getchar(); 28     while(ch<‘0‘||ch>‘9‘){if(ch==‘-‘)f=-1;ch=getchar();} 29     while(ch>=‘0‘&&ch<=‘9‘){x=10*x+ch-‘0‘;ch=getchar();} 30     return x*f; 31 } 32 int n,tot,f[maxn][maxn],t[maxn][5],go[maxn]; 33 char s[maxn]; 34 bool v[maxn]; 35 queue<int>q; 36 inline int id(char ch) 37 { 38     if(ch==‘A‘)return 0; 39     if(ch==‘G‘)return 1; 40     if(ch==‘C‘)return 2; 41     if(ch==‘T‘)return 3; 42 } 43 inline void insert() 44 { 45     memset(s,0,sizeof(s)); 46     scanf("%s",s+1);int len=strlen(s+1),now=1; 47     for1(i,len) 48     { 49         int x=id(s[i]); 50         if(!t[now][x])t[now][x]=++tot; 51         now=t[now][x]; 52     } 53     v[now]=1; 54 } 55 void bfs() 56 { 57     q.push(1); 58     while(!q.empty()) 59     { 60         int x=q.front(),y,j;v[x]|=v[go[x]];q.pop(); 61         for0(i,3) 62         { 63             j=go[x]; 64             while(j&&!t[j][i])j=go[j]; 65             if(t[x][i]) 66             { 67                 go[y=t[x][i]]=j?t[j][i]:1; 68                 q.push(y); 69             }else t[x][i]=j?t[j][i]:1; 70         } 71     } 72 } 73 int main() 74 { 75     freopen("input.txt","r",stdin); 76     freopen("output.txt","w",stdout); 77     int cs=0; 78     while(cin>>n&&n) 79     { 80         tot=1; 81         memset(t,0,sizeof(t)); 82         memset(v,0,sizeof(v)); 83         memset(go,0,sizeof(go)); 84         for1(i,n)insert(); 85         bfs(); 86         memset(s,0,sizeof(s)); 87         scanf("%s",s+1);n=strlen(s+1); 88         for0(i,n)for1(j,tot)f[i][j]=inf; 89         f[0][1]=0; 90         for0(i,n-1) 91          for1(j,tot) 92           if(f[i][j]!=inf) 93            for0(k,3) 94             if(!v[t[j][k]])  95              f[i+1][t[j][k]]=min(f[i+1][t[j][k]],f[i][j]+(k!=id(s[i+1]))); 96         int ans=inf; 97         for1(i,tot)ans=min(ans,f[n][i]); 98         printf("Case %d: %d\n",++cs,ans==inf?-1:ans); 99     }100     return 0;101 }

Biologists finally invent techniques of repairing DNA that contains segments causing kinds of inherited diseases. For the sake of simplicity, a DNA is represented as a string containing characters ‘A‘, ‘G‘ , ‘C‘ and ‘T‘. The repairing techniques are simply to change some characters to eliminate all segments causing diseases. For example, we can repair a DNA "AAGCAG" to "AGGCAC" to eliminate the initial causing disease segments "AAG", "AGC" and "CAG" by changing two characters. Note that the repaired DNA can still contain only characters ‘A‘, ‘G‘, ‘C‘ and ‘T‘.

You are to help the biologists to repair a DNA by changing least number of characters.

The last test case is followed by a line containing one zeros.