func_code_string: #include <bits/stdc++.h>   using namespace std;   const int MAXN = 2e5 + 3;   int a[MAXN], b[MAXN], p[MAXN];   int read() {     int x = 0, w = 1;     char c = getchar();     while (c <  0  || c >  9 ) {       if (c ==  - ) w = -1;       c = getchar();     }     while (c >=  0  && c <=  9 ) {       x = (x << 3) + (x << 1) + c - 48;       c = getchar();     }     return x * w;   }   int main() {     int n = read(), ans = 0;     for (int i = 1; i <= n; i++) a[i] = read(), p[a[i]] = 0;     for (int i = 1; i <= n; i++) b[i] = read(), p[b[i]] = i;     if (p[1]) {       int i, j;       for (i = 1; p[i] == p[1] + i - 1; i++)         ;       if (p[i - 1] == n) {         for (j = i; j <= n && p[j] <= j - i; j++)           ;         if (j > n) {           printf( %d n , n - i + 1);           return 0;         }       }     }     for (int i = 1; i <= n; i++) ans = max(ans, p[i] - (i - 1) + n);     printf( %d n , ans);     return 0;   }   