View Compilation Error

0_0_38902777_4221.cpp: In function 'int main()':
0_0_38902777_4221.cpp:4:9: error: '_int64' was not declared in this scope
    4 |         _int64 a, b, c;
      |         ^~~~~~
0_0_38902777_4221.cpp:5:38: error: 'a' was not declared in this scope
    5 |         while (scanf("%I64X %I64X", &a, &b) != EOF)
      |                                      ^
0_0_38902777_4221.cpp:5:42: error: 'b' was not declared in this scope
    5 |         while (scanf("%I64X %I64X", &a, &b) != EOF)
      |                                          ^
0_0_38902777_4221.cpp:7:17: error: 'c' was not declared in this scope
    7 |                 c = a + b;
      |                 ^