View Compilation Error

0_0_16393334_11444.cpp: In function 'int main()':
0_0_16393334_11444.cpp:19:30: error: 'a' was not declared in this scope
     while(scanf("%d%d%d",&n,&a,&b)!=EOF)
                              ^
0_0_16393334_11444.cpp:19:33: error: 'b' was not declared in this scope
     while(scanf("%d%d%d",&n,&a,&b)!=EOF)
                                 ^