int main() {
    long long int n;
    scanf("%lld", &n);
    int y = n % 2;
    switch (y) {
        case 0:
            printf("YES");
            break;
        case 1:
            int x = n % 3;
            switch (x) {
                case 0:
                    printf("YES");
                    break;
                case 1:
                    printf("NO");
                    break;
                case 2:
                    printf("NO");
                    break;
            }
            break;
    }
    return 0;
}

/sandbox/1/a.c:5:2: warning: implicitly declaring library function 'scanf' with type 'int (const char *restrict, ...)' [-Wimplicit-function-declaration]
        scanf("%lld",&n);
        ^
/sandbox/1/a.c:5:2: note: include the header <stdio.h> or explicitly provide a declaration for 'scanf'
/sandbox/1/a.c:10:4: warning: implicitly declaring library function 'printf' with type 'int (const char *, ...)' [-Wimplicit-function-declaration]
                        printf("YES");
                        ^
/sandbox/1/a.c:10:4: note: include the header <stdio.h> or explicitly provide a declaration for 'printf'
/sandbox/1/a.c:13:4: error: expected expression
                        int x=n%3;
                        ^
/sandbox/1/a.c:14:14: error: use of undeclared identifier 'x'
                    switch(x)
                           ^
2 warnings and 2 errors generated.