View Compilation Error

0_0_38678198_16895.cpp: In function 'void init()':
0_0_38678198_16895.cpp:18:9: error: 'f' was not declared in this scope
   18 |         f[0]=inv[0]=1;
      |         ^
0_0_38678198_16895.cpp:18:14: error: 'inv' was not declared in this scope; did you mean 'int'?
   18 |         f[0]=inv[0]=1;
      |              ^~~
      |              int
0_0_38678198_16895.cpp: In function 'int c(int, int)':
0_0_38678198_16895.cpp:26:16: error: 'f' was not declared in this scope
   26 |         return f[a]*inv[b]%mod*inv[a-b]%mod;
      |                ^
0_0_38678198_16895.cpp:26:21: error: 'inv' was not declared in this scope; did you mean 'int'?
   26 |         return f[a]*inv[b]%mod*inv[a-b]%mod;
      |                     ^~~
      |                     int