// 好像没什么好说的了
#include <stdio.h>
#include <vector>
#include <algorithm>
#include <string.h>
#include <map>
#include <queue>
#include <set>
#include <math.h>
#include <iostream>
using namespace std;
const int maxn=(int)260020;
const int MOD=(int)1e9+7;
struct nod{
    int num;int height;int ch[26];
    void init(){num=height=0;memset(ch,0,sizeof ch);}
};
nod trie[maxn];
int cnt=1;
const int root=1;
void insert(int cur,char s[510],int dig,int num){
  //  printf("cur %d str: %s cnt:%d\n",cur,s,cnt );
    int idx=s[dig]-‘A‘;//当前处理的字母
    if(trie[cur].ch[idx]==0) trie[cur].ch[idx]=++cnt;//如果未加入那么加入
    int ch=trie[cur].ch[idx];//
    trie[ch].height=dig;
    if(0==s[dig+1]) trie[ch].num+=num;
    else insert(ch,s,dig+1,num);
}
vector<char> q;
int dfs(int cur,int h){
    int res=0;
    for(int i=0;i<26;i++){
        if(trie[cur].ch[i]!=0){
            int ch= trie[cur].ch[i];
        //    q.push_back((char)(i+‘A‘));
            res+=dfs(ch,h);
            trie[cur].num+=max(trie[ch].num-1,0);
        //    q.erase(q.end()-1,q.end());
        }
    }

    if(trie[cur].height+1>=h&&trie[cur].num>0  ) {

        res++;
       // printf("%d trie[cur].height+1:%d trie[cur].num:%d ",res,trie[cur].height+1,trie[cur].num);
       // for(int j=0;j<q.size();j++)putchar(q[j]);putchar(‘\n‘);
    }
    return res;
}

void trieprint(int cur,int height){
    for(int i=0;i<26;i++){
        if(trie[cur].ch[i]!=0){
            q.push_back((char)(i+‘A‘));
            printf("trie[%d] No.%d: Next No.%d height:%d num:%d\n",cur,trie[cur].ch[i],trie[trie[cur].ch[i]].num,trie[cur].height,trie[cur].num);
            for(int j=0;j<q.size();j++)putchar(q[j]);putchar(‘\n‘);
            trieprint(trie[cur].ch[i],0);
            q.erase(q.end()-1,q.end());
        }
    }
}
char s[510];
int main(){
    #ifdef shuaishuai
    freopen("a.txt","r",stdin   );
    #endif // shuaishuai
    int n,k,m;
    while(scanf("%d%d",&n,&k)!=EOF,n+k!=0){
        cnt=1;
        for(int i=0;i<maxn;i++){
            trie[i].init();
        }
        for(int i=0;i<n;i++){
            scanf("%d%s",&m,s);
            insert(root,s,0,m);
        }
        trie[root].height=-1;
      //  trieprint(root,0);
        printf("%d\n",dfs(root,k));
    }
    return 0;
}