#include<bits/stdc++.h>
using namespace std;
 
#define ll long long
#define mx 200005
 
 
 
ll c0, c1, h, dp[mx];
int n;
string s1;
 
ll func(int pos)
{
    if(pos>=n)
        return 0;
    //ll &ret = dp[pos];
    ll a1=0, a2=0, a3=0;
    if(s1[0] == '0'){
        a1 = c0+func(pos+1);
        a2 = c1+h+func(pos+1);
    }
    else{
        a1 = c1+func(pos+1);
        a2 = c0+h+func(pos+1);   
    }
    cout<< "check\n";
    return min(a1, a2);
}
 
void solve()
{   
 
    cin >> n >> c0 >> c1 >> h >> s1;
    cout << func(0) << "\n";
 
}
 
int main()
{
    ios_base::sync_with_stdio(0);
    cin.tie(0);
 
    int t=1;
    cin >> t;
 
    while(t--)
        solve();
 
    return 0;
}

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