View Compilation Error

0_0_37321039_21269.cpp: In function 'int main()':
0_0_37321039_21269.cpp:4:2: error: '_int64' was not declared in this scope
  _int64 a,b;
  ^
0_0_37321039_21269.cpp:5:9: error: expected ';' before 'sum'
  _int64 sum;
         ^
0_0_37321039_21269.cpp:6:28: error: 'a' was not declared in this scope
  while(scanf("%l64X%l64X",&a,&b)!=EOF)
                            ^
0_0_37321039_21269.cpp:6:31: error: 'b' was not declared in this scope
  while(scanf("%l64X%l64X",&a,&b)!=EOF)
                               ^