func_code_string: #include <bits/stdc++.h>   using namespace std;   int n, m;   int arr[300001];   bool check(int val) {     if (val < 0) return false;     if (val >= m - 1) return true;     int prev = 0;     for (int i = int(1); i <= int(n); i++) {       if (arr[i] + val < prev) return false;       int r = (arr[i] + val) % m;       if (r < arr[i]) {         if (r >= prev)           continue;         else           prev = (prev > arr[i] ? prev : arr[i]);       } else {         prev = (prev > arr[i] ? prev : arr[i]);       }     }     return true;   }   int main() {     ios_base::sync_with_stdio(false);     cin.tie(0);     cout.tie(0);     cin >> n >> m;     for (int i = int(1); i <= int(n); i++) cin >> arr[i];     int l = 0, r = m - 1;     while (l <= r) {       int mid = (l + r) / 2;       if (check(mid) && (!check(mid - 1))) {         cout << mid;         return 0;       } else if (!check(mid))         l = mid + 1;       else         r = mid - 1;     }   }   