cbj

/*
 Author: 曹北健(37509)
 Result: AC
*/

#include <stdio.h>
#include <stdlib.h>
#include <math.h>
#include <string.h>
#include <ctype.h>
#pragma warning(disable:4996)
int main(){
    int n, i, j, a[128] = { 0 }, flag = 0, countof1 = 0, ser = 0, sermax = 0;
    scanf("%d", &n);
    for(i = 0;i < n;i++){
        scanf("%d", a + i);
    }
    if(n < 9){
        puts("-1");
    }
    else{
        for(i = 0;i < n - 9;i++){
            countof1 = 0;
            ser = 0;
            sermax = 0;
            for(j = 0;j < 9;j++){
                if(a[i + j] == 1){
                    countof1++;
                    ser++;
                    if(sermax < ser){
                        sermax = ser;
                    }
                }
                else{
                    ser = 0;
                }
            }
            if(sermax == 5 && countof1 == 7){
                flag = i + 9;
                break;
            }
        }
        printf("%d\n", flag > 0 ? flag : -1);
    }
    return 0;
}