foo.cpp:13:7: error: 'MAXN' was not declared in this scope
 int d[MAXN+10];
       ^
foo.cpp: In function 'int main()':
foo.cpp:17:18: error: 'd' was not declared in this scope
  for(i=0;i<n;i++)d[i]=read();
                  ^
foo.cpp:20:18: error: 'ok' was not declared in this scope
   if(ok((ri-le)/2)){
                  ^
foo.cpp:15:8: warning: unused variable 'j' [-Wunused-variable]
  int i,j,k;
        ^
foo.cpp:15:10: warning: unused variable 'k' [-Wunused-variable]
  int i,j,k;
          ^