#include <bits/stdc++.h>

using namespace std;

const int N = 1007;
const int M = 1007;
const int B = 107;

mt19937 mt(79);
uniform_int_distribution<int> uni1, uni2;

int range_random(int lvalue, int rvalue){
	uniform_int_distribution<int> uni = uniform_int_distribution<int>(lvalue, rvalue);

	return uni(mt);
}

int rnd_sh(int mod){
	return range_random(0, mod - 1);
}

int int_random(int lvalue, int rvalue){
	int random_integer;

	if(lvalue == 0){
		random_integer = uni1(mt);
	}
	else{
		random_integer = uni2(mt);
	}

	//cout << lvalue << " " << rvalue << " = " << random_integer << "\n";

	return random_integer; 
}

clock_t t;

inline bool time_left(double f){
	return (bool)((double)(clock() - t) / CLOCKS_PER_SEC <= f);
}

inline double time_passed(){
	return ((double)(clock() - t) / CLOCKS_PER_SEC);
}

int a[N][M];
int n, m, b;

struct solution{
	bitset<N> in;
	int score;
	int sum[M];
	int change[N];

	solution(){
		score = 0;
		for(int i = 1; i <= m; i++){
			sum[i] = 0;
		}

		for(int i = 1; i <= n; i++){
			in[i] = int_random(0, 1);
			if(in[i]){
				update_line(i, 1);
			}
		}
	}

	solution(const bitset<N> &in){
		this->in = in;
		score = 0;

		for(int i = 1; i <= m; i++){
			sum[i] = 0;
		}

		for(int i = 1; i <= n; i++){
			if(in[i]){
				update_line(i, 1);
			}
		}
	}	

	solution mutate(int cnt_it){
		solution ret = *this;

		for(int i = 1; i <= cnt_it; i++){
			int idx = int_random(1, n);

			ret.in[idx] = !ret.in[idx];

			if(ret.in[idx]){
				ret.update_line(idx, 1);
			}
			else{
				ret.update_line(idx, -1);
			}
		}

		return ret;
	}

	void try_all(){
		int pr_score = score;
		for(int i = 1; i <= n; i++){
			in[i] = !in[i];

			if(in[i]){
				update_line(i, 1);
			}
			else{
				update_line(i, -1);
			}

			if(score < pr_score){
				if(in[i]){
					update_line(i, -1);
				}
				else{
					update_line(i, 1);
				}
				in[i] = !in[i];
			}
			
			pr_score = score;
		}
	}

	void update_line(int idx, int mult){
		if(mult == 1){
			for(int i = 1; i <= m; i++){
				int pr_sum = sum[i];

				sum[i] += a[idx][i];

				if(sum[i] >= b){
					sum[i] -= b;
				}	
				else if(sum[i] < 0){
					sum[i] += b;
				}

				score += sum[i] * sum[i] - pr_sum * pr_sum;
			}
		}
		else{
			for(int i = 1; i <= m; i++){
				int pr_sum = sum[i];

				sum[i] -= a[idx][i];

				if(sum[i] >= b){
					sum[i] -= b;
				}	
				else if(sum[i] < 0){
					sum[i] += b;
				}

				score += sum[i] * sum[i] - pr_sum * pr_sum;
			}
		}
	}

	void output(){
		int k = 0;
		for(int i = 1; i <= n; i++){
			if(in[i]){
				k++;
			}
		}

		cout << k << "\n";

		for(int i = 1; i <= n; i++){
			if(in[i]){
				cout << i << "\n";
			}
		}
	}

	friend bool operator<(const solution &lvalue, const solution &rvalue){
		return lvalue.score > rvalue.score;
	}
};

solution find_best(int num, vector<int> v, solution sol){
	for(int i = 0; i < num; i++){
		int idx = v[i];
		bool boo = false;

		if(boo != sol.in[idx]){
			sol.in[idx] = boo;

			if(boo){
				sol.update_line(idx, 1);
			}
			else{
				sol.update_line(idx, -1);
			}
		}
	}

	solution best = sol;

	for(int i = 1; i < (1 << num); i++){
		for(int j = 0; j < num; j++){
			int idx = v[j];
			bool boo = (bool)(i & (1 << j));

			if(boo != sol.in[idx]){
				sol.in[idx] = boo;

				if(boo){
					sol.update_line(idx, 1);
				}
				else{
					sol.update_line(idx, -1);
				}
			}
		}	
		best = min(best, sol);
	}

	return best;
}

const int CNT_SOL = 10;
const int cnt_two = 8;

solution s[10];
int arr[N];

int main(){
	t = clock();

	ios::sync_with_stdio(false);
	cin.tie(NULL);

	freopen("subsetselection.in", "r", stdin);
	freopen("subsetselection.out", "w", stdout);

	cin >> n >> m >> b;

	uni1 = uniform_int_distribution<int>(0, 1);
	uni2 = uniform_int_distribution<int>(1, n);

	for(int i = 1; i <= n; i++){
		for(int j = 1; j <= m; j++){
			cin >> a[i][j];
			a[i][j] %= b;
		}
	}

	if(n == 20){
		vector<int> v;

		for(int i = 1; i <= n; i++){
			v.push_back(i);
		}

		solution best; 

		best = find_best(n, v, best);

		best.output();

		return 0;
	}

	for(int i = 0; i < CNT_SOL; i++){
		s[i].try_all();
	}

	while(time_left(1)){
		for(int i = 0; i < CNT_SOL; i++){
			s[i] = min(s[i], s[i].mutate(3));
		}
	}

	vector<int> v;

	for(int i = 0; i < cnt_two; i++){
		v.push_back(0);
	}

	for(int i = 1; i <= n; i++){
		arr[i] = i;
	}

	while(time_left(4.85)){
		random_shuffle(arr + 1, arr + n + 1, rnd_sh);

		for(int j = 1; j + cnt_two < n j += cnt_two){
			for(int i = 0; i < cnt_two; i++){
				v[i] = arr[i + j];
			}

			for(int i = 0; i < CNT_SOL; i++){
				int pr_score = s[i].score;
				s[i] = find_best(cnt_two, v, s[i]);
			}
		}
	}

	sort(s, s + CNT_SOL);

	s[0].output();

	return 0;
}