View Compilation Error

0_0_35547025_6130.cpp: In function 'int main()':
0_0_35547025_6130.cpp:4:27: error: 'a' was not declared in this scope
     while(scanf("%d %d", &a, &b) != EOF)
                           ^
0_0_35547025_6130.cpp:4:31: error: 'b' was not declared in this scope
     while(scanf("%d %d", &a, &b) != EOF)
                               ^