View Compilation Error

0_0_31157245_20403.cpp:10:4: error: 'maxn' was not declared in this scope
 }a[maxn]; 
    ^
0_0_31157245_20403.cpp: In function 'int main()':
0_0_31157245_20403.cpp:14:49: error: 'a' was not declared in this scope
    for(int i = 0; i < n; i++)   scanf("%d %d", &a[i].l, &a[i].r);
                                                 ^
0_0_31157245_20403.cpp:15:9: error: 'a' was not declared in this scope
    sort(a, a+n);
         ^