#include <bits/stdc++.h>
using namespace std;

//const int BIG_PRIME = 999983;
const int MAXN=200000000;
const int MAXR=7000000;
int N,M,B,gi=0,gr=0;

struct t_res {
    int prev, id, off;
};

vector<char> many_nums;
vector<t_res> many_res;
typedef long long ll;

int best_val = -1;
int best_off = -1;

int main() {
    double t = clock();
    ios_base::sync_with_stdio(false);
    cin.tie(NULL);
    #ifndef LOCAL
    freopen("subsetselection.in", "r", stdin);
    freopen("subsetselection.out", "w", stdout);
    #endif
    srand(123456789);

    cin>>N>>M>>B;

    // PUSH IT TO THE LIMIT
    int max_bytes = 250*1024*1024; 
    int max_many = max_bytes/(M+12);
    many_nums.resize(max_many*M+2);
    many_res.resize(max_many+2);

    for(int n=0;n<N;n++) {
        for(int m=0;m<M;m++) {
            int temp;
            cin>>temp;
            many_nums[gi]=temp%B;
            gi++;
        }
        many_res[n].prev=-1;
        many_res[n].id= n+1;
        many_res[n].off = n*M;
    }
    gr = N;
    random_shuffle(many_res.begin(),many_res.begin()+N);
    for(int n=0;n<N;n++) {
        int val = 0, off = many_res[n].off;
        for(int m=0;m<M;m++) {
            val+=(many_nums[off+m]*many_nums[off+m]);
        }
        if(val>best_val) {
            best_val = val;
            best_off = n;
        }
    }

   /* auto hash = [&](const int& a){ 
        int oa = many_res[a].off;
        ll hash = 0;
        for(int m=0;m<M;m++)hash=(hash*31+(int)many_nums[oa+m])%BIG_PRIME;
        return (size_t)hash;
    };

    auto equal = [&](const int& a, const int& b){
        int oa = many_res[a].off,ob = many_res[b].off;
        for(int m=0;m<M;m++) if(many_nums[oa+m]!=many_nums[ob+m]) return false;
        return true;
    };

    unordered_set<int,decltype(hash),decltype(equal)> seen(BIG_PRIME,hash,equal);
    */

    int try_count = N;
    for(int i=0;i<N && gr<max_many;i++) {
        for(int j=gr-1;j>=0 && gr<max_many;j--) {
            if(try_count%100==0) if((clock() - t) / CLOCKS_PER_SEC > 4.85) goto gg;

            bool gotyou=false;
            int cur = j;
            while(cur>=0) {
                if(many_res[cur].id == many_res[i].id) {
                    gotyou=true;
                    break;
                }
                cur = many_res[cur].prev;
            }
            if(gotyou)continue;

            int oa = many_res[i].off, ob = many_res[j].off;
            int val = 0,temp;
            for(int m=0;m<M;m++) {
                temp = ((int)many_nums[oa+m]+(int)many_nums[ob+m])%B;
                many_nums[gi+m]=temp;
                val+=temp*temp;
            }

            //if(seen.find(gr)==seen.end()) {
                many_res[gr].id = many_res[i].id;
                many_res[gr].prev = j;
                many_res[gr].off = gi;
                //seen.insert(gr);
                if(val>best_val) {
                    best_val = val;
                    best_off = gr;
                }
                gr++;
                gi+=M;
            //}
            try_count++;
        }
    }
    //cout<<"TIME OK BRO "<<try_count<<" "<<gr<<endl;
    gg:

    vector<int> chosen;
    int cur_off = best_off;
    do {
        chosen.push_back(many_res[cur_off].id);
        cur_off = many_res[cur_off].prev;
    } while(cur_off!=-1);

    sort(chosen.begin(),chosen.end());
    //chosen.erase(unique(chosen.begin(),chosen.end()),chosen.end());

    cout<<chosen.size()<<endl;
    for(int& c:chosen)cout<<c<<endl;

    return 0;
}