#include<bits/stdc++.h>
using namespace std;
int n,A,B,N;
char c[200100];
const int I=1e9;
int s1[201000],s2[200010],dp[201000];
struct BIT{
    int tr[401000];
    inline void gg(){for(int i=1;i<=N;i++)tr[i]=-I;}
    inline void ad(int x,int z){for(x+=n+1;x<=N;x+=(x&-x))tr[x]=max(tr[x],z);}
    inline int ask(int x){int s=-I;for(x+=n+1;x;x-=(x&-x))s=max(s,tr[x]);return s;}
    inline void cl(int x){for(x+=n+1;x<=N;x+=(x&-x))tr[x]=-I;}
}T;
void cdq(int l,int r){
    if(l==r){
        if(l)dp[l]=max(dp[l],dp[l-1]);
        return;
    }
    int mi=(l+r)>>1;
    cdq(l,mi);
    for(int t=l;t<=mi&&t-l<B;t++){
        vector<pair<int,int> >qb;
        for(int u=t;u<=r;u+=B)qb.push_back({s1[u],u});
        sort(qb.begin(),qb.end());
        for(auto it:qb){
            int u=it.second;
            if(u<=mi)T.ad(s2[u],dp[u]-u/B);
            else dp[u]=max(dp[u],T.ask(s2[u])+u/B);
        }
        for(auto it:qb)T.cl(s2[it.second]);
    }
    cdq(mi+1,r);
}
int main(){
    scanf("%d%d%d%s",&n,&A,&B,c+1),B+=A;N=n*2+2;T.gg();
    for(int i=1;i<=n;i++)s1[i]=s1[i-1]+(c[i]=='R'),s2[i]=s2[i-1]+(c[i]!='B');
    for(int i=0;i<=n;i++)s1[i]=A*(i/B)-s1[i],s2[i]=s2[i]-A*(i/B);
    cdq(0,n);printf("%d",dp[n]);
    return 0;
}