#include<iostream>

#include<cstdio>

#include<cstring>

#include<algorithm>

#define maxn 100050

using namespace std;

int n,m,op[maxn],a[maxn],ans=,ret=;

char s[maxn];

int check(int x,int bit)

{

    for (int i=;i<=n;i++)

    {

        int nowbit=(a[i]>>bit)&;

        if (op[i]==) x&=nowbit;

        else if (op[i]==) x|=nowbit;

        else x^=nowbit;

    }

    return x;

}

int main()

{

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

    for (int i=;i<=n;i++)

    {

        scanf("%s",s);scanf("%d",&a[i]);

        if (s[]=='A') op[i]=;

        else if (s[]=='O') op[i]=;

        else op[i]=;

    }

    for (int i=;i>=;i--)

    {

        int l=-,r=-;

        l=check(,i);r=check(,i);

        if (l==) ans+=(<<i);

        else if ((r==) && (ret+(<<i)<=m)) {ans+=(<<i);ret+=(<<i);}

    }

    printf("%d\n",ans);

    return ;

}