View Compilation Error

0_0_29792496_9804.cpp: In function 'void main_slove()':
0_0_29792496_9804.cpp:11:12: error: expected initializer before '+=' token
     ll ans += n * res + 7;
            ^
0_0_29792496_9804.cpp:12:22: error: 'ans' was not declared in this scope
     printf("%lld\n" ,ans);
                      ^