View Compilation Error

0_0_27463902_28330.cpp: In function 'int main(int, const char**)':
0_0_27463902_28330.cpp:11:23: error: 'a' was not declared in this scope
  while(scanf("%d %d",&a,&b) != EOF){
                       ^
0_0_27463902_28330.cpp:11:26: error: 'b' was not declared in this scope
  while(scanf("%d %d",&a,&b) != EOF){
                          ^