//#include "stdafx.h"

#include<cstdio>

#include<cctype>

#include<vector>

#include<algorithm>

#include<queue>

using namespace std;

?

??

int N=10, X=1, R=10, P=40, K=1;

char str[1010000]={1,1,1,1, 1,? ? 1,1,1,1, 1? ?};

char vis[1010000];

long? ?long sum=0;

priority_queue<pair<long long, int>> a;?

int main(){

? scanf("%d",&N);?

? scanf("%d",&X);? ??

? scanf("%d",&R);? ? ?

? scanf("%d",&P);? ? ?

? scanf("%d",&K);??

? scanf("%s",str); // */

?

int x;

? ?

?

long long cos;

for(? x=1;x<=N;x++)

{

if(str[x-1]=='1')cos=(N-(long long)x+1)*(P+R);

else cos=(N-(long long)x+1)*P;

a.push(pair<long long, int>(cos,x));

}

??

while (K)?

? ? {? ? ? ??

//printf("%d\n", a.top().first );

vis[a.top().second-1]= 1;

? ? ? ? a.pop();

K--;

? ? ? }?

long long val;

if(vis[0]) val=X+P;

else? ?if(str[0]=='1')val=X-R;

else val=X;

sum+=val;

for(? x=2;x<=N;x++)

{

if(vis[x-1])

val+=P;

else if(str[x-1]=='1')val-=R;

sum+=val;

}

printf("%lld\n",sum);?

return 0;

}