#include <bits/stdc++.h>

using namespace std;

int a[1000][1000];
int n, m, b;

int main() {
	ifstream fin("subsetselection.in");
	ofstream fout("subsetselection.out");
	fin>>n>>m>>b;
	int maxi=-1;
	vector<int> rje;
	for (int i=0; i<n; i++) {
		for (int j=0; j<m; j++) {
			fin>>a[i][j];
		}
	}
	int num=-1;
	switch (n)
	{
	case 20:
		num=9e5;
		break;
	case 200:
		num=5.5e4;
		break;
	case 1000:
		num=2e3;
		break;
	}
	for (int i=0; i<num; i++) {
		vector<int> v;
		for (int j=0; j<n; j++) {
			if (rand() < RAND_MAX / log10(n)) v.push_back(j);
		}
		if (v.empty()) continue;
		int zb=0;
		for (int j=0; j<m; j++) {
			int zb2=0;
			for (int k:v) {
				zb2+=a[k][j];
			}
			zb2%=b;
			zb+=zb2*zb2;
		}
		if (zb>maxi) {
			maxi=zb;
			rje.swap(v);
		}
	}
	fout<<rje.size()<<'\n';
	for (int i:rje) fout<<i+1<<'\n';
	return 0;
	
}