View Compilation Error

0_0_36262882_1991.cpp: In function 'void getMap()':
0_0_36262882_1991.cpp:30:22: error: 'n' was not declared in this scope
  for(int i = 1; i <= n; i++)
                      ^
0_0_36262882_1991.cpp: In function 'bool SPFA()':
0_0_36262882_1991.cpp:56:22: error: 'n' was not declared in this scope
  for(int i = 0; i <= n; i++)
                      ^
0_0_36262882_1991.cpp:80:23: error: 'n' was not declared in this scope
      if(used[E.to] >= n) 
                       ^
0_0_36262882_1991.cpp: In function 'int main()':
0_0_36262882_1991.cpp:92:21: error: 'n' was not declared in this scope
  while(scanf("%d", &n), n)
                     ^