#include <iostream>
#include <vector>
#include <algorithm>
using namespace std;

#define RREP(i,s,e) for (i = s; i >= e; i--)
#define rrep(i,n) RREP(i,n,0)
#define REP(i,s,e) for (i = s; i < e; i++)
#define rep(i,n) REP(i,0,n)
#define INF 100000000

typedef long long ll;

int main() {
    int i, n, k;
    int move[101], now[2][101];
    cin >> n >> k;
    REP (i,1,n+1) move[i] = i;
    rep (i,k) {
        int x, y;
        cin >> x >> y;
        swap(move[x],move[y]);
    }
    REP (i,1,n+1) now[0][i] = i;
    bool ok;
    int ans = 0;
    do {
        ok = true;
        REP (i,1,n+1) now[(ans+1)%2][i] = now[ans%2][move[i]];
        REP (i,1,n+1) ok &= now[(ans+1)%2][i] == i;
        ans++;
    } while (!ok);
    cout << ans << endl;
    return 0;
}