View Compilation Error

0_0_21778833_4210.cpp: In function 'void solve()':
0_0_21778833_4210.cpp:40:13: error: 'cot' was not declared in this scope
             cot = (((f[i]*f[j])%mod)*((C[m][i]*C[m-i][j])%mod))%mod;
             ^