#include<bits/stdc++.h>
using namespace std;
const int N = 1e5+10;
int T,C,pos[N],mp[N*2],mp2[N*2],ans,sum[N];
char op[N];
map<int,int> mp3;
int main(){
    cin>>T>>C;
    for(int i=1;i<=T;i++){
        int x;
        cin>>x;
        mp[x+N]=1;
    }
    int now=0;
    for(int i=1;i<=C;i++){
        cin>>op[i];
        if(op[i]=='L') now--;
        else if(op[i]=='R') now++;
        pos[i]=now;
    }
    for(int i=1;i<=C;i++){
        if(mp[pos[i]+N]==1&&op[i]=='F'){
            if(mp2[pos[i]+N]==0){
            	ans++;
            	sum[i]=sum[i-1]+1;
			}
			else{
				sum[i]=sum[i-1];
			}
            mp2[pos[i]+N]++;
        }
        else sum[i]=sum[i-1];
    }
    //L->R
    int cnt=0;
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='L'){
            ans=max(ans,cnt+sum[i-1]);
        }
        else if(op[i]=='F'){
            if(mp3[pos[i]+N+2]==0&&mp2[pos[i]+N+2]==0&&mp[pos[i]+N+2]==1){
                mp3[pos[i]+N+2]=1;
                cnt++;
            }
        }
    }
    mp3.clear();
    cnt=0;
    for(int i=1;i<=C;i++){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]++;
    }
    //L->F
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='L'){
            if(mp3[pos[i]+N+1]==0&&mp2[pos[i]+N+1]==0&&mp[pos[i]+N+1]==1){
                mp3[pos[i]+N+1]=1;
                cnt++;
            }
            ans=max(ans,cnt+sum[i-1]);
        }
        else if(op[i]=='F'){
            if(mp3[pos[i]+N+1]==0&&mp2[pos[i]+N+1]==0&&mp[pos[i]+N+1]==1){
                mp3[pos[i]+N+1]=1;
                cnt++;
            }
        }
    }
    mp3.clear();
    cnt=0;
    for(int i=1;i<=C;i++){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]++;
    }
    //R->L
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='R'){
            ans=max(ans,cnt+sum[i-1]);
        }
        else if(op[i]=='F'){
            if(mp3[pos[i]+N-2]==0&&mp2[pos[i]+N-2]==0&&mp[pos[i]+N-2]==1){
                mp3[pos[i]+N-2]=1;
                cnt++;
            }
        }
    }
    mp3.clear();
    cnt=0;
    for(int i=1;i<=C;i++){
    	if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]++;
    }
    //R->F
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='R'){
            if(mp3[pos[i]+N-1]==0&&mp2[pos[i]+N-1]==0&&mp[pos[i]+N-1]==1){
                mp3[pos[i]+N-1]=1;
                cnt++;
            }
            ans=max(ans,cnt+sum[i-1]);
        }
        else if(op[i]=='F'){
            if(mp3[pos[i]+N-1]==0&&mp2[pos[i]+N-1]==0&&mp[pos[i]+N-1]==1){
                mp3[pos[i]+N-1]=1;
                cnt++;
            }
        }
    }
    mp3.clear();
    cnt=0;
    for(int i=1;i<=C;i++){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]++;
    }
    //F->L
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='F'){
            ans=max(ans,cnt+sum[i-1]);
            if(mp3[pos[i]+N-1]==0&&mp2[pos[i]+N-1]==0&&mp[pos[i]+N-1]==1){
                mp3[pos[i]+N-1]=1;
                cnt++;
            }
        }
    }
    mp3.clear();
    cnt=0;
    for(int i=1;i<=C;i++){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]++;
    }
    //F->R
    for(int i=C;i>=1;i--){
        if(mp[pos[i]+N]==1&&op[i]=='F') mp2[pos[i]+N]--;
        if(op[i]=='F'){
            ans=max(ans,cnt+sum[i-1]);
            if(mp3[pos[i]+N+1]==0&&mp2[pos[i]+N+1]==0&&mp[pos[i]+N+1]==1){
                mp3[pos[i]+N+1]=1;
                cnt++;
            }
        }
    }
    cout<<ans<<endl;
    return 0;
}