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;

}