#include <cstdio>
int main()
{
	int M,T,Up,Flat,Down;
	while(scanf("%d%d%d%d%d",&M,&T,&Up,&Flat,&Down)!=EOF)
	{
		int time=0,ans=0;
		char ch;
		ch=getchar();
		for(int i=0;i!=T;++i)
		{
			scanf("%c%*c",&ch);
			if(ch=='u' || ch=='d')time+=(Up+Down);
			else if(ch=='f')time+=2*Flat;
			if(time<=M)++ans;
		}
		printf("%d\n",ans);
	}
	return 0;
}