def download():
    with open('input.txt') as inf:
        num, summa = map(int, inf.readline().split())
        array = []
        for i in range(num):
            array.append(inf.readline().rstrip())
    return summa, array

def date(array):
    new=[]
    for i in array:
        a,b = (i.split())
        new.append(int(a))
        new.append(int(b))
    return new

def result(summa, array):
    n=len(array)
    for i in range(0,n,2):
        check = 0
        for j in range(array[i+1]):
            check += array[i]
            if check==summa:
                return 'possible'
    return 'impossible'

def save(string):
    with open('output.txt','w') as outf:
        print(string,file=outf)

if __name__ == '__main__':
    print(download()[0])
    print(date(download()[1]))
    print(result(download()[0],date(download()[1])))
    save(result(download()[0],date(download()[1])))