URAL 1010 Discrete Function

#include<stdio.h>
#include<string.h>
#include<stdlib.h>
int N, f;
long long ans, x, px;
int main()
{
int i;
while(scanf("%d", &N) == 1)
{
ans = -1;
scanf("%lld", &px);
for(i = 1; i < N; i ++)
{
scanf("%lld", &x);
if(llabs(x - px) > ans)
ans = llabs(x - px), f = i;
px = x;
}
printf("%d %d\n", f, f + 1);
}
return 0;
}