#include<bits/stdc++.h>
#define int long long

using namespace std;

struct BigInt {
    static const int MOD = 1000000000;
    static const int N_BIT = 9;
    vector<int> nums;

    BigInt(const string s, int n) {
        int val = 0, base = 1;
        for(int i = n - 1; i >= 0; i--) {
            val += (s[i] - '0') * base;
            base *= 10;
            if(base == MOD) {
                nums.push_back(val);
                val = 0;
                base = 1;
            }
        }
        if(nums.empty() || val != 0) {
            nums.push_back(val);
        }
    }

    BigInt &operator= (const BigInt &&u) {
        nums = move(u.nums);
        return *this;
    }

    BigInt &operator+= (const BigInt &u) {
        nums.resize(max(nums.size(), u.nums.size()));
        int carry = 0;
        for(size_t i = 0; i < nums.size(); i++) {
            nums[i] += carry + (i < u.nums.size() ? u.nums[i] : 0);
            if(nums[i] >= MOD) {
                nums[i] -= MOD;
                carry = 1;
            } else {
                carry = 0;
            }
        }
        if(carry) {
            nums.push_back(carry);
        }
        return *this;
    }
    bool operator< (const BigInt &u) {
        if(nums.size() != u.nums.size()) {
            return nums.size() < u.nums.size();
        }
        for(size_t i = nums.size() - 1; i < nums.size(); i--) {
            if(nums[i] != u.nums[i]) {
                return nums[i] < u.nums[i];
            }
        }
        return false;
    }
};

ostream& operator<< (ostream &os, const BigInt &u) {
    ios states(nullptr);
    states.copyfmt(os);

    os << u.nums.back();
    for(int i = (int)u.nums.size() - 2; i >= 0; i--) {
        os << setw(BigInt::N_BIT) << setfill('0') << u.nums[i];
    }

    os.copyfmt(states);
    return os;
}

void solve(){
    int n,m;
    string s;
    cin>>n>>m>>s;
    BigInt res(s,n);
    vector<int>d(m+1);
    auto dfs=[&](auto dfs,int id)->void{
        if(id>m){
            int sum=0;
            auto dx=d;
            for(int i=1;i<=m;++i) dx[i]+=dx[i-1],sum+=dx[i];
            sum=n-sum;
            if(sum%(m+1)) return;
            sum/=(m+1);
            dx[0]=sum;
            for(int i=1;i<=m;++i) dx[i]+=dx[i-1];
            if(*min_element(dx.begin(),dx.end())<=0) return;
            // for(auto x:dx) cerr<<x<<" ";
            // cerr<<endl;
            BigInt ans("",0);
            int lst=0;
            for(int i=0;i<=m;++i){
                string t=s.substr(lst,dx[i]);
                ans+=BigInt(t,dx[i]);
                lst+=dx[i];
            }
            if(ans<res) res=move(ans);
            return;
        }
        for(int i=-1;i<=1;++i){
            d[id]=i;
            dfs(dfs,id+1);
        }
    };
    dfs(dfs,1);
    cout<<res<<"\n";
}

signed main(){
    ios::sync_with_stdio(false);
    cin.tie(0);
    int T;cin>>T;
    while(T--) solve();
}