#include <bits/stdc++.h>
using namespace std;
typedef signed long long ll;

#undef _P
#define _P(...) (void)printf(__VA_ARGS__)
#define FOR(x,to) for(x=0;x<to;x++)
#define ITR(x,c) for(__typeof(c.begin()) x=c.begin();x!=c.end();x++)
#define ALL(a) (a.begin()),(a.end())
#define ZERO(a) memset(a,0,sizeof(a))
#define MINUS(a) memset(a,0xff,sizeof(a))
//-------------------------------------------------------

int N,K;
int A[2][101],R[101],rev[101];
void solve() {
	int i,j,k,l,r,x,y; string s;
	
	cin>>N>>K;
	FOR(i,N) R[i]=i;
	while(K--) {
		cin>>x>>y;
		swap(R[x-1],R[y-1]);
	}
	FOR(i,N) rev[R[i]]=i, A[0][i]=i;
	
	FOR(x,10000) {
		int cur=x%2,tar=cur^1;
		FOR(i,N) A[tar][i]=A[cur][rev[i]];
		int ok=1;
		FOR(i,N) if(A[tar][i]!=i) ok=0;
		if(ok==1) return _P("%d\n",x+1);
	}
	
	
}


int main(int argc,char** argv){
	string s;int i;
	if(argc==1) ios::sync_with_stdio(false);
	FOR(i,argc-1) s+=argv[i+1],s+='\n';
	FOR(i,s.size()) ungetc(s[s.size()-1-i],stdin);
	solve(); return 0;
}