View Compilation Error

0_0_36000831_15680.cpp:4:1: error: '_int64' does not name a type
 _int64 f[N][2],a[N];
 ^
0_0_36000831_15680.cpp: In function 'int dfs(int, bool, bool)':
0_0_36000831_15680.cpp:8:5: error: 'f' was not declared in this scope
  if(f[pos][last]&&!limit) return f[pos][last];
     ^
0_0_36000831_15680.cpp:9:16: error: 'a' was not declared in this scope
  int x=limit ? a[pos] : 9;
                ^
0_0_36000831_15680.cpp:16:13: error: 'f' was not declared in this scope
  if(!limit) f[pos][last]=ans;
             ^
0_0_36000831_15680.cpp: In function 'int solve(int)':
0_0_36000831_15680.cpp:24:3: error: 'a' was not declared in this scope
   a[len++]=n%10;
   ^