View Compilation Error

0_0_30477394_14887.cpp: In function 'int solve(int)':
0_0_30477394_14887.cpp:573:29: error: 'ksm' was not declared in this scope
  inv[n+2]=ksm(fac[n+2],mod-2);
                             ^
0_0_30477394_14887.cpp: In function 'int main()':
0_0_30477394_14887.cpp:583:61: error: 'ksm' was not declared in this scope
   printf("%d\n",(solve(n-1)-solve(m)+mod+1ll*m*ksm(m+2,mod-2)%mod)*(n+1)%mod);
                                                             ^