View Compilation Error

0_0_20393994_9575.cpp: In function 'int main()':
0_0_20393994_9575.cpp:5:33: error: expected primary-expression before '=' token
   while(scanf("%d %d", &a, &b)!==EOF)
                                 ^
0_0_20393994_9575.cpp:8:24: error: 'sum' was not declared in this scope
       printf(" %d \n", sum);
                        ^