View Compilation Error

0_0_37132886_27187.cpp: In function 'int main()':
0_0_37132886_27187.cpp:4:5: error: '_int64' was not declared in this scope
     _int64 sum=0x00;
     ^
0_0_37132886_27187.cpp:5:12: error: expected ';' before 'a'
     _int64 a=0x00,b=0x00;
            ^
0_0_37132886_27187.cpp:6:31: error: 'a' was not declared in this scope
     while(scanf("%I64x%I64x",&a,&b)!=EOF)
                               ^
0_0_37132886_27187.cpp:6:34: error: 'b' was not declared in this scope
     while(scanf("%I64x%I64x",&a,&b)!=EOF)
                                  ^
0_0_37132886_27187.cpp:8:9: error: 'sum' was not declared in this scope
         sum=a+b;
         ^