View Compilation Error

0_0_38650768_29299.cpp: In function 'int main()':
0_0_38650768_29299.cpp:22:55: error: 'ia' was not declared in this scope
   for (int i = 1; i <= n + 1; ++i) ans = (ans + dp[n][ia]) % mod;
                                                       ^~
0_0_38650768_29299.cpp:22:55: note: suggested alternative: 'i'
   for (int i = 1; i <= n + 1; ++i) ans = (ans + dp[n][ia]) % mod;
                                                       ^~
                                                       i