View Compilation Error

0_0_20626935_22886.cpp: In function 'bool check(int)':
0_0_20626935_22886.cpp:12:23: error: 'n' was not declared in this scope
  for( int i = 1; i <= n; i++ ){
                       ^
0_0_20626935_22886.cpp: In function 'int main()':
0_0_20626935_22886.cpp:28:4: error: 'low' was not declared in this scope
    low = min( low, num[i] );
    ^