/*
aabacad

dcdbdaa 
acdbdaa
adcbdaa
aacbdaa
aabcdaa
aabcada
aabacda
aabacad
*/
#include<bits/stdc++.h>
#define ll long long
using namespace std;
const int mod=1e9+7;
const int maxm=5e2+10;
namespace io {
    const int SIZE = (1 << 21) + 1;
    char ibuf[SIZE], *iS, *iT, obuf[SIZE], *oS = obuf, *oT = oS + SIZE - 1, c, qu[55]; int f, qr;
    // getchar
    #define gc() (iS == iT ? (iT = (iS = ibuf) + fread (ibuf, 1, SIZE, stdin), (iS == iT ? EOF : *iS ++)) : *iS ++)
    // print the remaining part
    inline void flush () {
        fwrite (obuf, 1, oS - obuf, stdout);
        oS = obuf;
    }
    // putchar
    inline void putc (char x) {
        *oS ++ = x;
        if (oS == oT) flush ();
    }
    template<typename A>
    inline bool read (A &x) {
        for (f = 1, c = gc(); c < '0' || c > '9'; c = gc()) if (c == '-') f = -1;else if(c==EOF)return 0;
        for (x = 0; c <= '9' && c >= '0'; c = gc()) x = x * 10 + (c & 15); x *= f;
        return 1;
    }
    inline bool read (char &x) {
        while((x=gc())==' '||x=='\n' || x=='\r');
        return x!=EOF;
    }
    inline bool read(char *x){
        while((*x=gc())=='\n' || *x==' '||*x=='\r');
        if(*x==EOF)return 0;
        while(!(*x=='\n'||*x==' '||*x=='\r'||*x==EOF))*(++x)=gc();
        *x=0;
        return 1;
    }
    template<typename A,typename ...B>
    inline bool read(A &x,B &...y){
        return read(x)&&read(y...);
    }
    template<typename A>
    inline bool write (A x) {
        if (!x) putc ('0'); if (x < 0) putc ('-'), x = -x;
        while (x) qu[++ qr] = x % 10 + '0',  x /= 10;
        while (qr) putc (qu[qr --]);
        return 0;
    }
    inline bool write (char x) {
        putc(x);
        return 0;
    }
    inline bool write(const char *x){
        while(*x){putc(*x);++x;}
        return 0;
    }
    inline bool write(char *x){
        while(*x){putc(*x);++x;}
        return 0;
    }
    template<typename A,typename ...B>
    inline bool write(A x,B ...y){
        return write(x)||write(y...);
    }
    //no need to call flush at the end manually!
    struct Flusher_ {~Flusher_(){flush();}}io_flusher_;
}
using io :: read;
using io :: putc;
using io :: write;
char s[maxm];
string dp[maxm];
string Min(string s1,string s2)
{
	int n=s1.length(),m=s2.length(),flag=0;
	for(int i=0;i<min(n,m);i++)
	{
		if(s1[i]==s2[i]) continue;
		if(s1[i]>s2[i]) flag=1;
		else flag=-1;
		break;
	}
	if(flag==0) return n>m?s2:s1;
	if(flag==1) return s2;
	return s1;
}
int main()
{
	int T;
	read(T);
	while(T--)
	{
		int n,k;
		read(n,k);
		read(s+1);
		//int n=strlen(s+1);
		dp[1]=s[1];
		if(s[1]=='a'+k-1||s[1]=='a') dp[1]="a";
		else dp[1][0]--;
		//cout<<"dp[1]="<<dp[1]<<endl;
		for(int i=2;i<=n;i++)
		{
			string temp="a",t1="a";
			t1[0]=s[i];
			if(s[i]=='a'+k-1||s[i]=='a') t1="a";
			else t1[0]--;
			dp[i]=dp[i-1]+t1;
			temp=dp[i-1].substr(0,i-2)+s[i]+dp[i-1][i-2];
			dp[i]=Min(dp[i],temp);
			temp=dp[i-2]+t1+s[i-1];
			dp[i]=Min(dp[i],temp);
			if(i>2)
			{
				temp=dp[i-2].substr(0,i-3)+s[i]+dp[i-2][i-3]+s[i-1];
				dp[i]=Min(dp[i],temp);
			}
			//cout<<"dp["<<i<<"]="<<dp[i]<<endl;
		}
		for(int i=0;i<n;i++) printf("%c",dp[n][i]);
		printf("\n");
	}
	return 0;
}