#include <stdint.h>
 
unsigned long long sum(unsigned long num)
{
    unsigned long long result = 0, previous = 0;
 
    for(unsigned long i = 1; i <= num; i++)
    {
        result += i;
        if(result < previous)
        {
            printf("Wraparound at : %lu\n", i);
            break;
        }
        previous = result;
    }
    return result;
}
 
int main(void)
{
    printf("%llu\n", sum(1000000));
    printf("%llu\n", sum(6074001001UL));
}

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