#include<bits/stdc++.h>
using namespace std;
string s,t;
#define int long long
int n,m,w[400005];
int qzh[400005];
inline void solve2()
{
    if(n<m) {puts("-1"); return ;}
    memset(qzh,0,sizeof(qzh));
    for(int i=1;i<=n;++i) qzh[i]=qzh[i-1]+w[i];
    int ans=qzh[m]-qzh[0];
    for(int i=m;i<=n;++i) ans=max(ans,qzh[i]-qzh[i-m]);
    cout<<qzh[n]-ans<<endl;
}
inline void solve()
{
    cin>>n>>m>>s>>t;
    for(int i=1;i<=n;++i) cin>>w[i];
    solve2();
}
signed main()
{
    // freopen("letter.in","r",stdin);
    // freopen("letter.out","w",stdout);
    int T; cin>>T; while(T--) solve();
    return 0;
}