View Compilation Error

0_0_20508069_5851.cpp: In function 'int main()':
0_0_20508069_5851.cpp:4:2: error: 'in' was not declared in this scope
  in a,b;
  ^
0_0_20508069_5851.cpp:5:16: error: 'a' was not declared in this scope
  scanf("%d%d",&a,&b);
                ^
0_0_20508069_5851.cpp:5:19: error: 'b' was not declared in this scope
  scanf("%d%d",&a,&b);
                   ^