View Compilation Error

0_0_23123313_24395.cpp:2:1: error: '_int64' does not name a type
 _int64 num(_int64 n)
 ^
0_0_23123313_24395.cpp: In function 'int main()':
0_0_23123313_24395.cpp:17:1: error: '_int64' was not declared in this scope
 _int64 a,b,i,max;
 ^
0_0_23123313_24395.cpp:18:27: error: 'a' was not declared in this scope
 while(scanf("%I64d%I64d",&a,&b)!=EOF)
                           ^
0_0_23123313_24395.cpp:18:30: error: 'b' was not declared in this scope
 while(scanf("%I64d%I64d",&a,&b)!=EOF)
                              ^
0_0_23123313_24395.cpp:20:1: error: 'max' was not declared in this scope
 max=0;
 ^
0_0_23123313_24395.cpp:21:5: error: 'i' was not declared in this scope
 for(i=(a<b?a:b);i<=(b>a?b:a);i++)
     ^
0_0_23123313_24395.cpp:22:9: error: 'num' was not declared in this scope
 if(num(i)>max)
         ^