View Compilation Error

0_0_17932497_6340.cpp: In function 'void init()':
0_0_17932497_6340.cpp:37:5: error: 'f' was not declared in this scope
     f[0] = 1;
     ^
0_0_17932497_6340.cpp: In function 'long long int Lucas(long long int, long long int)':
0_0_17932497_6340.cpp:56:21: error: 'f' was not declared in this scope
         ret = ret * f[nn] * pow_mod (f[kk] * f[nn-kk] % mod, mod - 2) % mod;
                     ^