#include <bits/stdc++.h>   using namespace std;   long long int pow(long long int a, long long int b) {     long long int ans = 1;     while (b) {       if (b & 1) ans *= a;       a *= a;       b >>= 1;     }     return ans;   }   long long int powmod(long long int a, long long int b) {     long long int ans = 1;     while (b) {       if (b & 1) ans = (ans * a) % 10000000007;       a = (a * a) % 10000000007;       b >>= 1;     }     return ans;   }   bool ispal(string &a) {     for (int i = 0; i < a.size() / 2; i++)       if (a[i] != a[a.size() - i - 1]) return false;     return true;   }   unsigned long long int sum(unsigned long long int n) {     unsigned long long int x = 0;     while (n) {       x += n % 10;       n /= 10;     }     return x;   }   int main() {     {       ios_base::sync_with_stdio(false);       cin.tie(NULL);       cout.tie(NULL);     };     unsigned long long int n, m;     cin >> n >> m;     unsigned long long int ans = 0, p = 1;     for (int i = 0; i < m; i++) {       unsigned long long int x;       cin >> x;       ans += (p > x) ? n - p + x : x - p;       p = x;     }     cout << ans << endl;     return 0;   }   