#include <bits/stdc++.h>

using namespace std;

int n, m, b;
int S[1023][1023];
//random_device randDev;
//mt19937 randGen(randDev());


clock_t startTime;
inline bool haveTime() {
   return (clock() - startTime) < 4.6 * CLOCKS_PER_SEC;
}

int permToN[1024];

void chooseK(int k) {
   for (int i = 0; i < k-1; ++i) {
      int swapIdx =
            i + (rand() % (n-i));
            //uniform_int_distribution<>(i, n-1)(randGen);
      if (swapIdx != i) swap(permToN[i], permToN[swapIdx]);
   }
}

inline int calcScore(int k) {
   int res = 0;
   for (int i = 0; i < m; ++i) {
      int resi = 0;
      for (int ji = 0; ji < k; ++ji) {
         resi += S[i][permToN[ji]];
      }
      resi %= b;
      res += resi*resi;
   }
   return res;
}

int main() {
   startTime = clock();
   freopen("subsetselection.in", "r", stdin);
   freopen("subsetselection.out", "w", stdout);

   scanf("%d %d %d", &n, &m, &b);
   for (int i = 0; i < n; ++i) {
      for (int j = 0; j < m; ++j) {
         scanf("%d", &S[j][i]);
      }
   }

   for (int i = 0; i < n; ++i) permToN[i]=i;

   int bestRes = 0;
   int best[1024];
   int bestk = 0;
   int ITERATIONS = 0;
   //uniform_int_distribution<> randDistribution(1,n);

   #ifndef ONLINE_JUDGE
   clock_t timeInCalcScore = 0;
   clock_t timeInChooseK = 0;
   clock_t aa,bb;
   #endif

   while (haveTime()) {
      ITERATIONS++;
      int k =
            1 + (rand() % n);
            //randDistribution(randGen);
      #ifndef ONLINE_JUDGE
      bb=clock();
      #endif
      chooseK(k);
      #ifndef ONLINE_JUDGE
      aa=clock();
      timeInChooseK += aa-bb;
      #endif

      #ifndef ONLINE_JUDGE
      bb = clock();
      #endif
      int score = calcScore(k);
      #ifndef ONLINE_JUDGE
      aa = clock();
      timeInCalcScore += aa-bb;
      #endif

      if (score > bestRes) {
         #ifndef ONLINE_JUDGE
         fprintf(stderr,
            "IMPROVEMENT: OLD: %d, NEW: %d\n",
            bestRes, score);
         #endif
         bestRes = score;
         bestk = k;
         //for (int i = 0; i < k; ++i) best[i] = permToN[i];
         memcpy(best, permToN, k * sizeof(int));
      }
   }

   #ifndef ONLINE_JUDGE
   fprintf(stderr, "Optimization iterations: %d\n", ITERATIONS);
   fprintf(stderr, "Time in calcScore: %.5lf seconds\n", 1.0*timeInCalcScore / CLOCKS_PER_SEC);
   fprintf(stderr, "Time in chooseK: %.5lf seconds\n", 1.0*timeInChooseK / CLOCKS_PER_SEC);
   #endif
   printf("%d\n", bestk);
   for (int i = 0; i < bestk; ++i) {
      printf("%d\n", best[i]+1);
   }
   return 0;
}