View Compilation Error

0_0_24222523_18615.cpp: In function 'int main()':
0_0_24222523_18615.cpp:5:26: error: 'a' was not declared in this scope
     while (scanf("%d%d",&a,&b))
                          ^
0_0_24222523_18615.cpp:5:29: error: 'b' was not declared in this scope
     while (scanf("%d%d",&a,&b))
                             ^