View Compilation Error

0_0_13759115_18168.cpp: In function 'int main()':
0_0_13759115_18168.cpp:4:24: error: 'a' was not declared in this scope
    while(scanf("%d%d",&a,&b)!=EOF)
                        ^
0_0_13759115_18168.cpp:4:27: error: 'b' was not declared in this scope
    while(scanf("%d%d",&a,&b)!=EOF)
                           ^