View Compilation Error

0_0_38634995_22677.cpp:8:15: error: 'n' was not declared in this scope
 vector<int> v(n + 1), w(n + 1);
               ^
0_0_38634995_22677.cpp:8:25: error: 'n' was not declared in this scope
 vector<int> v(n + 1), w(n + 1);
                         ^