View Compilation Error

0_0_17459319_4936.cpp:6:1: error: '_int64' does not name a type
 _int64 solve(_int64 n)
 ^
0_0_17459319_4936.cpp: In function 'int main()':
0_0_17459319_4936.cpp:30:5: error: '_int64' was not declared in this scope
     _int64 T,l,r,cas = 1,ans;
     ^
0_0_17459319_4936.cpp:31:20: error: 'T' was not declared in this scope
     scanf("%I64d",&T);
                    ^
0_0_17459319_4936.cpp:34:30: error: 'l' was not declared in this scope
         scanf("%I64d %I64d",&l,&r);
                              ^
0_0_17459319_4936.cpp:34:33: error: 'r' was not declared in this scope
         scanf("%I64d %I64d",&l,&r);
                                 ^
0_0_17459319_4936.cpp:35:9: error: 'ans' was not declared in this scope
         ans = solve(r)-solve(l-1);
         ^
0_0_17459319_4936.cpp:35:22: error: 'solve' was not declared in this scope
         ans = solve(r)-solve(l-1);
                      ^
0_0_17459319_4936.cpp:36:39: error: 'cas' was not declared in this scope
         printf("Case #%I64d: %I64d\n",cas++,ans);
                                       ^