func_code_string: #include <bits/stdc++.h>   using namespace std;   const int Imx = 2147483647;   const long long Lbig = 2e18;   const int mod = 1e9 + 7;   struct fastio {     char s[100000];     int it, len;     fastio() { it = len = 0; }     inline char get() {       if (it < len) return s[it++];       it = 0;       len = fread(s, 1, 100000, stdin);       if (len == 0)         return EOF;       else         return s[it++];     }     bool notend() {       char c = get();       while (c ==     || c ==   n ) c = get();       if (it > 0) it--;       return c != EOF;     }   } _buff;   inline long long getnum() {     long long r = 0;     bool ng = 0;     char c;     c = _buff.get();     while (c !=  -  && (c <  0  || c >  9 )) c = _buff.get();     if (c ==  - ) ng = 1, c = _buff.get();     while (c >=  0  && c <=  9 ) r = r * 10 + c -  0 , c = _buff.get();     return ng ? -r : r;   }   template <class T>   inline void putnum(T x) {     if (x < 0) putchar( - ), x = -x;     register short a[20] = {}, sz = 0;     while (x) a[sz++] = x % 10, x /= 10;     if (sz == 0) putchar( 0 );     for (int i = sz - 1; i >= 0; i--) putchar( 0  + a[i]);   }   inline char getreal() {     char c = _buff.get();     while (c ==     || c ==   n ) c = _buff.get();     return c;   }   int n;   int ask(int x, int y) {     printf( ? %d %d n , x, y);     fflush(stdout);     int ans;     scanf( %d , &ans);     return ans;   }   int a[5011], b[5011];   int A[5011], B[5011];   bool hs[5011];   int tans[5011];   bool check() {     memset(hs, 0, sizeof(hs));     for (int i = 0; i < n; i++) {       if (A[i] < 0 || A[i] >= n || hs[A[i]]) return false;       hs[A[i]] = 1;     }     memset(hs, 0, sizeof(hs));     for (int i = 0; i < n; i++) {       if (B[i] < 0 || B[i] >= n || hs[B[i]]) return false;       hs[B[i]] = 1;     }     for (int i = 0; i < n; i++) {       if (A[B[i]] != i) return false;     }     return true;   }   int main() {     scanf( %d , &n);     for (int i = 0; i < n; i++) {       a[i] = ask(i, 0);     }     for (int i = 0; i < n; i++) {       b[i] = ask(0, i);     }     int cnt = 0;     for (int i = 0; i < n; i++) {       A[0] = i;       B[0] = A[0] ^ a[0];       for (int j = 1; j < n; j++) {         A[j] = A[0] ^ a[0] ^ a[j];         B[j] = B[0] ^ b[0] ^ b[j];       }       if (check()) {         cnt++;         for (int j = 0; j < n; j++) tans[j] = A[j];       }     }     printf( ! n );     printf( %d n , cnt);     for (int i = 0; i < n; i++) printf( %d%c , tans[i], i + 1 < n ?     :   n );     fflush(stdout);     return 0;   }   