cbj

/*
 Author: 曹北健(37509)
 Result: AC Submission_id: 4160279
 Created at: Sun Mar 13 2022 23:06:22 GMT+0800 (China Standard Time)
 Problem: 5394  Time: 2 Memory: 1708
*/

#include <stdio.h>
int main(){
    int n, i, j, cnt;
    int num[1000] = { 0 };
    scanf("%d", &n);
    for(i = 0;i < n;i++){
        scanf("%d", &num[i]);
    }
    for(i = 0;i < n - 8;i++){
        if((num[i] != 1) && (num[i + 1] != 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] != 1) && (num[i + 8] != 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] == 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] != 1) && (num[i + 6] != 1) && (num[i + 7] == 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] == 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] != 1) && (num[i + 6] == 1) && (num[i + 7] == 1) && (num[i + 8] != 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] == 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] != 1) && (num[i + 6] == 1) && (num[i + 7] != 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] != 1) && (num[i + 1] == 1) && (num[i + 2] == 1) && (num[i + 3] != 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] == 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] != 1) && (num[i + 2] == 1) && (num[i + 3] != 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] == 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] == 1) && (num[i + 2] != 1) && (num[i + 3] != 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] == 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] != 1) && (num[i + 1] == 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] != 1) && (num[i + 7] == 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] == 1) && (num[i + 2] != 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] == 1) && (num[i + 8] != 1)){
            printf("%d", i + 9);
            goto out;
        }
        else if((num[i] == 1) && (num[i + 1] != 1) && (num[i + 2] == 1) && (num[i + 3] == 1) && (num[i + 4] == 1) && (num[i + 5] == 1) && (num[i + 6] == 1) && (num[i + 7] != 1) && (num[i + 8] == 1)){
            printf("%d", i + 9);
            goto out;
        }
    }
    printf("-1");

out:
    ;
    return 0;
}