Very plain LargestCommonMultiple calculator

lcm.c

#include <stdio.h>

typedef unsigned long long u64;

u64 lcm(u64 f, u64 s)
{
	u64 n1, n2;
	if(f > s) { n1 = f; n2 = s; }
	else { n1 = s; n2 = f; }

	u64 i;
	for(i = 1; i <= n2; i++) if(!((n1 * i) % n2)) return n1 * i;
	return n2;
}

u64 parseU(char* wat)
{
	u64 n = 0;
	u64 m = 1;
	char* s = wat;
	while(*wat) wat++;
	while(wat != s) { n += (*(--wat) - '0') * m; m *= 10; }
	return n;
}

int main(int argc, char** argv)
{
	if(argc < 3)
	{
		puts("Error: at least 2 args are required!");
		return 1;
	}

	u64 n = parseU(argv[1]);
	int i = 2;
	for(; i != argc; i++) n = lcm(n, parseU(argv[i]));
	printf("Result: %llu\n", n);
	return 0;
}