// Why Stop Now...
#include "bits/stdc++.h"
using ll = long long;
using namespace std;
#define el "\n"
#define n_l "\n"
#define dbg(...) cout << "[" << #__VA_ARGS__ << "]: "; cout << to_string(__VA_ARGS__) << endl
template <typename T, size_t N> int SIZE(const T (&t)[N]){ return N; } template<typename T> int SIZE(const T &t){ return t.size(); } string to_string(const string s, int x1=0, int x2=1e9){ return '"' + ((x1 < s.size()) ? s.substr(x1, x2-x1+1) : "") + '"'; } string to_string(const char* s) { return to_string((string) s); } string to_string(const bool b) { return (b ? "true" : "false"); } string to_string(const char c){ return string({c}); } template<size_t N> string to_string(const bitset<N> &b, int x1=0, int x2=1e9){ string t = ""; for(int __iii__ = min(x1,SIZE(b)),  __jjj__ = min(x2, SIZE(b)-1); __iii__ <= __jjj__; ++__iii__){ t += b[__iii__] + '0'; } return '"' + t + '"'; } template <typename A, typename... C> string to_string(const A (&v), int x1=0, int x2=1e9, C... coords); int l_v_l_v_l = 0, t_a_b_s = 0; template <typename A, typename B> string to_string(const pair<A, B> &p) { l_v_l_v_l++; string res = "(" + to_string(p.first) + ", " + to_string(p.second) + ")"; l_v_l_v_l--; return res; } template <typename A, typename... C> string to_string(const A (&v), int x1, int x2, C... coords) { int rnk = rank<A>::value; string tab(t_a_b_s, ' '); string res = ""; bool first = true; if(l_v_l_v_l == 0) res += n_l; res += tab + "["; x1 = min(x1, SIZE(v)), x2 = min(x2, SIZE(v)); auto l = begin(v); advance(l, x1); auto r = l; advance(r, (x2-x1) + (x2 < SIZE(v))); for (auto e = l; e != r; e = next(e)) { if (!first) { res += ", "; } first = false; l_v_l_v_l++; if(e != l){ if(rnk > 1) { res += n_l; t_a_b_s = l_v_l_v_l; }; } else{ t_a_b_s = 0; } res += to_string(*e, coords...); l_v_l_v_l--; } res += "]"; if(l_v_l_v_l == 0) res += n_l; return res; } void dbgm(){;} template<typename Heads, typename... Tails> void dbgm(Heads H, Tails... T){ cout << to_string(H) << " | "; dbgm(T...); }
#define dbgm(...) cout << "[" << #__VA_ARGS__ << "]: "; dbgm(__VA_ARGS__); cout << endl
clock_t time_p=clock();
void TLL() {
    time_p=clock()-time_p;
    cerr<<"Time Taken : "<<(float)(time_p)/CLOCKS_PER_SEC<<"\n";
}

template<typename T>
void print(T v){
  for(auto i:v){
    cout<<i<<" ";
  }
  cout<<el;
}


int main(){
int t=1; //cin>>t;
while (t--){
    string a,b; cin>>a>>b;
    ll x1=0,x2=0;
    for(auto i:a) x1+=i-'0';
    for(auto i:b) x2+=i-'0';
    cout<<max(x1,x2)<<el;


}



}


#include <bits/stdc++.h>
using namespace std;

int dp[1<<18];
int n,m;
int edge[20];

void init(){
	for(int i=0;i<n;i++)
		edge[i] = edge[i] | (1<<i);
}

int main(){
	cin>>n>>m;
	init();
	while(m--){
		int a,b,a1,b1;
		cin>>a>>b;
		a1=a-1 ,b1=b-1;        //二进制从 0 开始 ,点的序列号改为:0~n-1 
		edge[a1] = edge[a1] | (1<<b1);  //将 b-1位改成 1 
		edge[b1] = edge[b1] | (1<<a1);
	}
	
	memset(dp,0x3f,sizeof(dp));
	
	dp[0] = 0;
	
	for(int state = 1; state < (1<<n) ; state++){
		//判定集合state是否是完全图 
		int complete = 1; 
		for(int j=0;j<n;j++){
			if( state>>j&1 && (edge[j]&state) != state){
				complete = 0;
			}
		}
		
		//完全图，则强连通分量为 1 
		if(complete) dp[state] = 1;
		
		//枚举当前集合的所有子集 
		//state二进制位上为 0的，j该位必须为 0
		for(int j=state; j>0; j=(j-1)&state){
			dp[state] = min(dp[state] , dp[state-j]+dp[j]);
		}
	}
	
	cout<<dp[(1<<n)-1]<<endl;
}