View Compilation Error

0_0_33867769_3542.cpp: In function 'int main()':
0_0_33867769_3542.cpp:4:22: error: 'a' was not declared in this scope
  while(scanf("%d%d",&a,&b)!=EOF){
                      ^
0_0_33867769_3542.cpp:4:25: error: 'b' was not declared in this scope
  while(scanf("%d%d",&a,&b)!=EOF){
                         ^
0_0_33867769_3542.cpp:5:19: error: expected primary-expression before ')' token
   printf("%d",a+b;)
                   ^