int main()
{
    long int a,b,c;
    scanf("%lu %lu %lu",&a,&b,&c);
    if (a>=b&&a>=c){
        printf("%lu",a);
    }else if (b>=a&&b>=c){
        printf("%lu",b);
    }else if (c>=b&&c>=a){
        printf("%lu",c);
    }
    return 0;
}

求助，结果一直有一个WA