#include<bits/stdc++.h>
#define ll long long 
#define mp make_pair 
#define f(i,n) for(int i=0;i<n;i++) 
#define F first 
#define S second 
#define pb push_back 

using namespace std;

void test(){
	ll n,m;
	cin>>n>>m;
	ll o = 0, e = 0;
	f(i,n){
		string s;
		cin>>s;
		int cnt = 0;
		f(j,m){
			if(s[j]=='1')cnt++;
		}
		if(cnt%2==0)e++;
		else o++;
	}
	ll res = o*e;
	cout<<res<<"\n";
	
}

int main(){
	std::ios::sync_with_stdio(false);
	cin.tie(0);
	cout.tie(0);
	int tests=1;
	// cin>>tests;
	while(tests--){
		test();
	}
}

// 2021-04-17 16:11:14
// clang-format off
#include <bits/stdc++.h>
#ifdef LOCAL
#include "lib/debug.hpp"
#else
#define debug(...) 1
#endif
#define ALL(a) (a).begin(), (a).end()
#define RALL(a) (a).rbegin(), (a).rend()
#define rep(i, n) REP(i, 0, (n))
#define repc(i, n) REPC(i, 0, (n))
#define REP(i, n, m) for (int i = (int)(n); i < (int)(m); i++)
#define REPC(i, n, m) for (int i = (int)(n); i <= (int)(m); i++)
#define REPCM(i, n, m) for (int i = (int)(n); i >= (int)(m); i--)
template<class T> inline bool chmin(T& a, const T& b) { if (a > b) { a = b; return true; } else return false; }
template<class T> inline bool chmax(T& a, const T& b) { if (a < b) { a = b; return true; } else return false; }
using namespace std;
using ll = long long;
using ld = long double;
using P = pair<int, int>;

// clang-format on
void answer() {
  ll x, y, z;
  cin >> x >> y >> z;
  ll ans = -1;
  rep(a, 2000000) {
    if (a * x < y * z) chmax(ans, ll(a));
  }
  cout << ans << '\n';
}

int main() {
  std::ios::sync_with_stdio(false);
  std::cin.tie(0);
  answer();
  return 0;
}