View Compilation Error

0_0_30137945_20637.cpp:9:4: error: 'maxn' was not declared in this scope
 }f[maxn];
    ^
0_0_30137945_20637.cpp: In function 'int main()':
0_0_30137945_20637.cpp:32:21: error: 'f' was not declared in this scope
                     f[pos].a[i]=b[i];
                     ^
0_0_30137945_20637.cpp:39:17: error: 'f' was not declared in this scope
                 f[pos].a[0]=n;
                 ^
0_0_30137945_20637.cpp:44:32: error: 'f' was not declared in this scope
         for(int i=1;i<=pos;i++)f[i].len=n;
                                ^
0_0_30137945_20637.cpp:45:14: error: 'f' was not declared in this scope
         sort(f+1,f+pos+1,cmp);
              ^