/*************************************************************************

> File Name: gas_station.cpp

> Author: dulun

> Mail: dulun@xiyoulinux.org

> Created Time: 2015年12月17日 星期四 21时24分14秒

************************************************************************/

#include<iostream>

#include<stdio.h>

using namespace std;

int gas[] = {31,32,33,34,35,36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30};

int cost[] = {36,37,38,39,40,41,42,43,44,45,46,47,48,49,50,1,2,3,4,5,6,7,8,9,10,11,12,13,14,15,16,17,18,19,20,21,22,23,24,25,26,27,28,29,30,31,32,33,34,35};

bool yes(int s, int n, int left[])

{

int have = left[s];

int i;

if(s == n-1) i = 0;

else i = s+1;

while(i != s)

{

have += left[i];

if(have < 0) return -1;

if(i == n-1) i = 0;

else i++;

}

return 1;

}

int main()

{

int n = sizeof(gas) / sizeof(int);

int left[1000] = {0};

int station = -1;

for(int i = 0; i < n; i++)

{

left[i] = gas[i] - cost[i];

}

for(int i = 0; i < n; i++)

{

if(left[i] < 0) continue;

if(yes(i, n, left) == 1) {station = i; break;}

}

cout<<station;

}