Untitled

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

const int maxn = 1e3+10;
int b[maxn];

int main()
{
    int n, m;
    cin >> n >> m;

    for(int i = 1; i <= m; i++) {
        int x, y;
        cin >> x >> y;

        if(x > y) swap(x, y);

        for(int j = x+1; j <= y; j++) b[j] = 1;
    }

    int ans = n + 1, here = 0;
    for(int i = 1; i <= n+1; i++) {
        if(b[i] == 0) ans += 2 * here, here = 0;
        else here += b[i];
    }

    cout << ans << endl;

    return 0;
}