foo.cpp: In function 'int main()':
foo.cpp:11:16: error: unable to find numeric literal operator 'operator"" c'
 if ((a[0]+b[0]-2c[n-1])%26==0)
                ^
foo.cpp:14:27: error: expected ')' before 'b'
 else if ((a[0] + c[0] - 2 b[n - 1]) % 26 == 0)
                           ^
foo.cpp:15:15: error: expected ')' before ';' token
 for (i = n - 1; i >= 0; i--)
               ^
foo.cpp:15:19: warning: statement has no effect [-Wunused-value]
 for (i = n - 1; i >= 0; i--)
                   ^
foo.cpp:15:28: error: expected ';' before ')' token
 for (i = n - 1; i >= 0; i--)
                            ^
foo.cpp:17:1: error: 'else' without a previous 'if'
 else
 ^