#include <bits/stdc++.h>
clock_t __t = clock();
namespace my_std {
using namespace std;
mt19937 rng(chrono::steady_clock::now().time_since_epoch().count());
template <typename T>
inline T rnd(T l, T r) {
  return uniform_int_distribution<T>(l, r)(rng);
}
template <typename T>
inline bool chkmax(T &x, T y) {
  return x < y ? x = y, 1 : 0;
}
template <typename T>
inline bool chkmin(T &x, T y) {
  return x > y ? x = y, 1 : 0;
}
template <typename T>
inline void read(T &t) {
  t = 0;
  char f = 0, ch = getchar();
  double d = 0.1;
  while (ch > '9' || ch < '0') f |= (ch == '-'), ch = getchar();
  while (ch <= '9' && ch >= '0') t = t * 10 + ch - 48, ch = getchar();
  if (ch == '.') {
    ch = getchar();
    while (ch <= '9' && ch >= '0') t += d * (ch ^ 48), d *= 0.1, ch = getchar();
  }
  t = (f ? -t : t);
}
template <typename T, typename... Args>
inline void read(T &t, Args &...args) {
  read(t);
  read(args...);
}
char __sr[1 << 21], __z[20];
int __C = -1, __zz = 0;
inline void Ot() { fwrite(__sr, 1, __C + 1, stdout), __C = -1; }
inline void print(int x) {
  if (__C > 1 << 20) Ot();
  if (x < 0) __sr[++__C] = '-', x = -x;
  while (__z[++__zz] = x % 10 + 48, x /= 10)
    ;
  while (__sr[++__C] = __z[__zz], --__zz)
    ;
  __sr[++__C] = '\n';
}
void file() {}
inline void chktime() {}
long long ksm(long long x, int y) {
  long long ret = 1;
  for (; y; y >>= 1, x = x * x)
    if (y & 1) ret = ret * x;
  return ret;
}
}  // namespace my_std
using namespace my_std;
int n, m;
char a[20][1100000];
long long c[1100000], w[1100000];
void FWT(long long *a) {
  long long x, y;
  for (int i = (0); i <= (n - 1); i++)
    for (int j = (0); j <= ((1 << n) - 1); j++)
      if (j >> i & 1)
        x = a[1 << i ^ j], y = a[j], a[1 << i ^ j] = x + y, a[j] = x - y;
}
void iFWT(long long *a) {
  long long x, y;
  for (int i = (0); i <= (n - 1); i++)
    for (int j = (0); j <= ((1 << n) - 1); j++)
      if (j >> i & 1)
        x = a[1 << i ^ j], y = a[j], a[1 << i ^ j] = x + y, a[j] = x - y;
  for (int j = (0); j <= ((1 << n) - 1); j++) a[j] >>= n;
}
int main() {
  file();
  read(n, m);
  for (int i = (0); i <= (n - 1); i++) cin >> (a[i] + 1);
  for (int j = (1); j <= (m); j++) {
    int x = 0;
    for (int i = (0); i <= (n - 1); i++) x += int(a[i][j] - '0') << i;
    ++c[x];
  }
  for (int i = (0); i <= ((1 << n) - 1); i++)
    w[i] = min(__builtin_popcount(i), n - __builtin_popcount(i));
  FWT(c), FWT(w);
  for (int i = (0); i <= ((1 << n) - 1); i++) w[i] = w[i] * c[i];
  iFWT(w);
  long long ans = n * m;
  for (int i = (0); i <= ((1 << n) - 1); i++) chkmin(ans, w[i]);
  cout << ans;
  return 0;
}
