#include<iostream>
#include<stdio.h>
#include<algorithm>
#define maxn 100005
char a[maxn]={0};
int b[maxn]={0};
using namespace std;
int main()
{
	freopen("racing.in","r",stdin);
	freopen("racing.out","w",stdout);
	int i,M,T,U,F,D,tot=0;
	scanf("%d %d %d %d %d",&M,&T,&U,&F,&D);
	for(i=1;i<=T;i++)
	{
		cin>>a[i];
	}
	for(i=1;i<=T;i++)
	{
		if(a[i]=='u')
		{
			b[i]=U;
		}
		if(a[i]=='f')
		{
			b[i]=F;
		}
		if(a[i]=='d')
		{
			b[i]=D;
		}
	}
	for(i=1;;i++)
	{
		if(a[i]=='u'||a[i]=='d')
		{
			tot=tot+U+D;
			if(tot>M)
			{
				i=i-1;
			}
			if(tot==M)
			{
				break;
			}
		}
		if(a[i]=='f')
		{
			tot=tot+F+F;
			if(tot>M)
			{
				i=i-1;
			}
			if(tot==M)
			{
				break;
			}
		}
		if(tot>=M)
		{
			break;
		}

	}
	printf("%d",i);
	return 0;
}