View Compilation Error

0_0_26797978_28473.cpp: In function 'int main()':
0_0_26797978_28473.cpp:5:25: error: 'a' was not declared in this scope
     while(scanf("%d%d",&a,&b)!=EOF){//存在多组输入
                         ^
0_0_26797978_28473.cpp:5:28: error: 'b' was not declared in this scope
     while(scanf("%d%d",&a,&b)!=EOF){//存在多组输入
                            ^