// SubsetSelection.cpp : This file contains the 'main' function. Program execution begins and ends there.
//

#define _CRT_SECURE_NO_WARNINGS
#include <stdio.h>
#include <chrono>

using namespace std::chrono;

steady_clock::time_point end = steady_clock::now() + milliseconds(4950);
bool not_expired() { return steady_clock::now() < end; }

int N, M, B;

unsigned char A[1000][1000], T[1000], T1[1000][1000];
int I[1000];
int MI[1000];
int maxSum = -1, maxLevel = 0;

void iterate(int level, int numLevels)
{
	if (level >= 0)
	{
		for (I[level] = level; I[level] < I[level + 1] && not_expired(); I[level]++) {
			iterate(level - 1, numLevels);
		}
	}
	else
	{
		int total = 0;
		for (int i = 0; i < M; i++)
		{
			int sum = 0;
			for (int j = 0; j < numLevels; j++)
			{
				sum += A[I[j]][i];
				if (sum >= B) sum -= B;
			}
			total += sum * sum;
		}
		if (maxSum < total)
		{
			maxSum = total;
			maxLevel = numLevels;
			for (int j = 0; j < numLevels; j++)
				MI[j] = I[j];
		}
	}
}

int main()
{
	FILE* fin = fopen("subsetselection.in", "rt");
	fscanf(fin, "%d %d %d", &N, &M, &B);

	for (int i = 0; i < N; i++) {
		int sum = 0;
		for (int j = 0; j < M; j++) {
			int v;
			fscanf(fin, "%d", &v);
			A[i][j] = (unsigned char)v;
			sum += v * v;
		}
		// check single sets
		if (maxSum < sum) {
			maxSum = sum;
			MI[0] = i;
			maxLevel = 1;
		}
	}
	fclose(fin);

	// check sum of all sets
	int total = 0;
	for (int i = 0; i < M && not_expired(); i++) {
		int sum = 0;
		for (int j = 0; j < N; j++) {
			sum += A[j][i];
			if (sum >= B) sum -= B;
		}
		T[i] = sum;
		total += sum * sum;
	}
	if (maxSum < total) {
		maxSum = total;
		maxLevel = N;
		for (int i = 0; i < N; i++)
			MI[i] = i;
	}

	// check two sets
	for (int i = 1; i < N && not_expired(); i++) {
		for (int j = 0; j < i; j++) {
			int sum = 0;
			for (int k = 0; k < M; k++) {
				int sij = A[i][k] + A[j][k];
				if (sij >= B) sij -= B;
				sum += sij * sij;
			}
			//printf("s(%d,%d)=%d\n", i, j, sum);
			if (maxSum < sum) {
				maxSum = sum;
				MI[0] = i;
				MI[1] = j;
				maxLevel = 2;
			}
		}
	}

	for (int i = 0; i < N && not_expired(); i++) {
		// check sum of all sets
		int total = 0;
		for (int j = 0; j < M && not_expired(); j++) {
			int sum = T[j] - A[i][j];
			if (sum < 0) sum += B;
			T1[i][j] = sum;
			total += sum * sum;
		}
		if (maxSum < total) {
			maxSum = total;
			maxLevel = N - 1;
			for (int k = 0, j = 0; k < N; k++) {
				if (i == k) continue;
				MI[j++] = k;
			}
		}
	}

	for (int i = 0; i < N - 1 && not_expired(); i++) {
		for (int k = i + 1; k < N && not_expired(); k++) {
			// check sum of all sets
			int total = 0;
			for (int j = 0; j < M && not_expired(); j++) {
				int sum = T1[i][j] - A[k][j];
				if (sum < 0) sum += B;
				total += sum * sum;
			}
			if (maxSum < total) {
				maxSum = total;
				maxLevel = N - 2;
				for (int l = 0, j = 0; l < N; l++) {
					if (i == l || k == l) continue;
					MI[j++] = l;
				}
			}
		}
	}

	for (int i = 3; i <= N - 3 && not_expired(); i++) {
		I[i] = N;
		iterate(i - 1, i);
	}
	//// check all possible combinations until time expires
	//for (int i = 3, j = N - 2; i <= j && not_expired(); i++, j--) {
	//	I[i] = N;
	//	iterate(i - 1, i);
	//	if (i < j)
	//	{
	//		I[j] = N;
	//		iterate(j - 1, j);
	//	}
	//}

	FILE* fout = fopen("subsetselection.out", "wt");
	fprintf(fout, "%d\n", maxLevel);
	for(int i = 0; i < maxLevel; i++)
		fprintf(fout, "%d\n", MI[i] + 1);
	fclose(fout);
}