1.如果绳长l >= 桥高s，那么重力势能全部转化为动能wgh = 1/2wv^2,

求出到达地面的速度v，如果v > 10,则 Killed by the impact.

否则能存活James Bond survives.

2.如果绳长l < s,则找绳的最大形变量，当绳到达最大长度l2时，重力势能全部转化为弹性势能wgh = 1/2kl1^2,

绳子的最大长度l2=本身长度l+形变量l1，如果绳的最大长度l2<s,则人在半空中Stuck in the air.

否则重力势能转化为动能和弹性势能（此时绳的形变量 = （s - l））wgh = 1/2k(s - l)^2 + 1/2wv^2,

求出到地面的速度v,如果v>10，则Killed by the impact.

否则能存活James Bond survives.

#include<stdio.h>
#include<stdlib.h>
#include<math.h>
#include<string.h>

#define g 9.81

using namespace std;

int main()
{
    double k, l, s, w;
    while(scanf("%lf%lf%lf%lf", &k, &l, &s, &w), k + l + s + w)
    {
        if(l >= s)
        {
            double v = sqrt(2 * g * s);
            if(v > 10)
                printf("Killed by the impact.\n");
            else
                printf("James Bond survives.\n");
            continue;
        }
        else
        {
            double l1 = sqrt(1.0 * 2 * w * g * s / k);
            if(l + l1 < s)
                printf("Stuck in the air.\n");
            else
            {
                double v = sqrt(1.0 * (2 * w * g * s - k * (s - l) * (s - l)) / w);
                if(v > 10)
                    printf("Killed by the impact.\n");
                else
                    printf("James Bond survives.\n");
            }
        }
    }
    return 0;
}