/in/foo.cc: In function 'int main()':
/in/foo.cc:22:26: warning: statement has no effect [-Wunused-value]
                 dp[i][j] == 0;
                 ~~~~~~~~~^~~~
/in/foo.cc:30:47: warning: array subscript is below array bounds [-Warray-bounds]
                 dp[i][j] = max(dp[i - 1][j - 1] + a[i], dp[i][j]);
                                ~~~~~~~~~~~~~~~^