def main():
    flag = False
    print('введите строки')
    str = ''
    number = 0
    while str != 'СТОП':
        number += 1
        str = input()
        if 'кот' in str or 'Кот' in str:
            flag = 1
            temp = number
    if flag == 1:
        print(temp)
    else:
        print('-1')
main()