#include <bits/stdc++.h> 
using namespace std;
const int N = 100010; 
long long n,m,s;
long long a[N];
char ch[N],c[N];
int suan(int u,int x){
    for(int i = 1;i <= n;i++){
        int b = (a[i] >> u) & 1;
        if(c[i] == 'A')x &= b;
        else if(c[i] == 'O')x |= b;
        else x ^= b;
    }//遍历n便 
    return x;
}
int main(){
    freopen("sleep.in","r",stdin);
    freopen("sleep.out","w",stdout);
    scanf("%lld%lld",&n,&m);
    for(int i = 1;i <= n;i++){
        cin>>ch>>a[i];
        c[i] = ch[0];
    }
    int u = 0;//u为初始攻击力 
    for(int i = 29;i >= 0;i--){//从最高位开始，尽量让结果大 
        int x = 0,y = 0;
        x = suan(i,1);//x为初始攻击力第i位为1的结果 
        y = suan(i,0);//y为初始攻击力第i位为0的结果 
        if(u + (1 << i) <= m && x > y){
           u += (1 << i),s += (x << i); 
        }//第i为1结果大，u第i位变为1，s最后结果变大 
        else {
            /*u += (0 << i) */s += (y << i);
        }//第i为0结果大，u第i位变为0，s最后结果变大
    }
    printf("%lld\n",s);
    
    return 0;
    
}