#include<bits/stdc++.h>
int n,m,ans,x,a1=0,a2=-1;
//-1的补码:11111111111... 
char str[5];
int main(){scanf("%d%d",&n,&m);while(n--){scanf("%s%d",str,&x);if(str[0]=='A') a1&=x, a2&=x;if(str[0]=='X') a1^=x, a2^=x;if(str[0]=='O') a1|=x, a2|=x;}for(int j=29;~j;--j){if(a1>>j&1) ans+=1<<j;else if(a2>>j&1&&(1<<j)<=m){ans+=1<<j,m-=1<<j;}} printf("%d",ans);return 0;
}