#include<bits/stdc++.h>
// #define int long long
#define mod 1000000007ll
#define pii pair<int,int>
#define fi first
#define se second
#define mems(x,y) memset(x,y,sizeof(x))
#define pb push_back
#define db double
using namespace std;
const int maxn=50010;
inline int read(){
	int x=0,f=1;
	char ch=getchar();
	while(ch<'0'||ch>'9'){if(ch=='-')f=-1;ch=getchar();}
	while(ch>='0'&&ch<='9'){x=(x<<3)+(x<<1)+(ch-48);ch=getchar();}
	return x*f;
}

int n,k,ans;
char s[maxn];
int dp[2][1<<6][4],cur;
int f[9],g[9];
void work(){
	scanf("%s",s+1);n=strlen(s+1);k=read();
	dp[0][0][0]=1;
	for(int i=1;i<=n;i++){
		for(int s=0;s<(1<<k+k);s++){
			for(int j=0;j<=k;j++)dp[i&1][s][j]=0;
		}
		int ss=0,mn=26,cnt=0;
		for(int p=max(i-k,1);p<=min(i+k,n);p++)ss|=1<<s[p]-'A';
		for(int c=0;c<26;c++)if(!(ss&(1<<c)))++cnt,mn=c;
		ss|=1<<mn;
		for(int s=0;s<(1<<k+k);s++){
			for(int j=0;j<=k;j++)if(dp[cur][s][j]){
				g[0]=max(i-1-k,0)-j;
				for(int p=1;p<=2*k;p++)g[p]=g[p-1]+((s>>p-1)&1);
				for(int c=0;c<26;c++)if(ss&(1<<c)){
					bool fl=1;int t=0;
					for(int p=0;p<=2*k;p++){
						f[p]=max({p?f[p-1]:0,g[p]+(1<=i-k+p&&i-k+p<=n&&c==::s[i-k+p]-'A'),g[p+1]});
						if(f[p]+max(n-i,n-(i-k+p))<n-k){fl=0;break;}
						if(p&&f[p-1]!=f[p])t|=(1<<p-1);
					}
					if(fl){
						int val=1ll*(c==mn?cnt:1)*dp[cur][s][j]%mod;
						(dp[i&1][t][max(i-k,0)-f[0]]+=val)%=mod;
					}
				}
			}
		}
		cur^=1;
	}
	for(int s=0;s<(1<<k+k);s++){
		for(int j=0;j<=k;j++){
			int v=max(n-k,0)-j;
			for(int ii=0;ii<k;ii++)if(s&(1<<ii))++v;
			if(v>=n-k)(ans+=dp[n&1][s][j])%=mod;
		}
	}
	printf("%lld\n",ans);
}

int T;
signed main(){
	T=1;
	while(T--)work();
}