#!/usr/bin/env python3
(n, c), best, current = map(int, input().split()), (1e6, "impossible"), 0
for i, a in enumerate(map(int, input().split())):
    current += a
    if current < (n - i) * c:
        best = min(best, (current // c, i))
    current = max(0, current - c)
print(best[1])