View Compilation Error

0_0_31865737_5699.c: In function 'main':
0_0_31865737_5699.c:11:3: error: unknown type name '_int64'
   _int64 sum=0;
   ^
0_0_31865737_5699.c:14:21: error: expected expression before ')' token
      for(i=0;i<n;i==)
                     ^