#include <iostream>
#include <cstdlib>
#include <cstdio>
#include <cstring>
#include <algorithm>
using namespace std;
char a[100010]={0};
int main()
{
    freopen("racing.in","r",stdin);
    freopen("racing.out","w",stdout);
    int sj=0;
	int cd;
	int m,t,u,f,d;
    cin>>t>>m>>u>>f>>d;
    for(int i=0;i<m;i++){
		cin>>a[i];
    }
    f=f*2;
    for(int i=0;i<m;i++){
		if(a[i]=='u'&&sj+u<=t) sj=sj+u+d;cd=i;
		if(a[i]=='f'&&sj+f<=t) sj=sj+f;cd=i;
		if(a[i]=='d'&&sj+u<=t) sj=sj+d+u;cd=i;
	}
	/*int k=t-sj;
	if(k>=u&&k>=f&&k>=d){
		for(int i=m-1;i>0;i++){
			if(a[i]=='u'&&sj+u<=t) sj=sj+u;cd=i;
			if(a[i]=='f'&&sj+f<=t) sj=sj+f;cd=i;
			if(a[i]=='d'&&sj+u<=t) sj=sj+d;cd=i;
		}
	}*/
	cd--;
	cout<<cd;
    return 0;
}