//Saptak_Roy_Turja
#include<bits/stdc++.h>
#define ll long long int
using namespace std;
int main()
{
    int t;
    cin>>t;
    while(t--){
        ll n,a,b,c=1,i;
        string s;
        cin>>n>>a>>b>>s;
        for(i=1;i<n;i++){
            if(s[i]!=s[i-1]){
                c++;
            }
        }
        if(b>=0){
            cout<<n*(a+b)<<'\n';
        }
        else {
            cout<<n*a+b*(c/2+1)<<'\n';
        }
    }
}
