#include <cstdlib>
#include <iostream>
#include <cstdio>
#include <cstring>
#include <cmath>
#include <algorithm>
using namespace std;
typedef long long LL;

int sum[100010];

int main()
{
    freopen("racing.in","r",stdin);
    freopen("racing.out","w",stdout);
    int M,T,U,F,D;
    scanf("%d%d%d%d%d\n",&M,&T,&U,&F,&D);
    for(int i=1;i<=T;i++)
    {
		char t;
		scanf("%c\n",&t);
		if(t=='u') sum[i]=U+F;
		else if(t=='f') sum[i]=F+U;
		else if(t=='d') sum[i]=D*2;
	}
	int i=1,ans=0;
	while(ans+sum[i]<=M)
	{
		ans+=sum[i];
		i++;
	}
	printf("%d\n",i);
    //system("PAUSE");
    return 0;
}