#include<bits/stdc++.h>
using namespace std;
const int N = 200050/7;
struct big{
int n;
short a[N];
}ans, nw;
bool inti = 1;
int n, k;
string st;
big operator + (big a, big b) {
int m = max(a.n, b.n);
big c;
c.n = m;
c.a[m + 1] = 0;
for (int i = a.n + 1;i <= m;++ i) a.a[i] = 0;
for (int i = b.n + 1;i <= m;++ i) b.a[i] = 0;
for (int i = 1;i <= m;++ i) {
c.a[i] = a.a[i] + b.a[i];
if (c.a[i] > 9) {
c.a[i] -= 10;
c.a[i+1] += 1;
}
}
if (c.a[m + 1] != 0) ++ c.n;
return c;
}
bool operator < (big &a, big &b) {
if (a.n != b.n) {
return a.n < b.n;
}
for (int i = a.n;i >= 1;-- i) {
if (a.a[i] != b.a[i])
return (a.a[i] < b.a[i]);
}
return false;
}
big cp(int x, int y) {
big c;
c.n = 0;
for (int i = y;i >= x;-- i) {
c.a[++c.n] = st[i - 1] - '0';
}
return c;
}
void dfs(int d, int j, big nw, int len) {
if (d == k) {
if (abs(n - j + 1 - len) > 1) return;
big nw2 = cp(j, n);
nw = nw + nw2
if (inti || nw < ans) {
ans = nw;
inti = false;
}
return ;
}
if (j > n) return;
for (int h = -1;h <= 1;++ h){
int i = h + len;
if (i <= 0) continue;
big nw2 = nw + cp(j,j + i - 1); //!!!
if (j + i <= n + 1)
dfs(d + 1, j + i, nw2, i);
}
return;
}
int main(){
ios::sync_with_stdio(false); cin.tie(0);
int tcase = 0;
cin >> tcase;
while (tcase --) {
inti = 1;
cin >> n >> k;
++ k;
cin >> st;
int L = max((int)((double)2 * n / k - (k - 1))/2,1);
int R = min(L + k - 1, n);
for (int i = L;i <= R;++ i)
dfs(2, i + 1, nw = cp(1,i), i);
for (int i = ans.n;i >= 1;-- i) cout << ans.a[i];
cout << endl;
}
return 0;
}