D, G = list(map(int, input().split()))

P = []

C = []

for i in range(D):

    p, c = list(map(int, input().split()))

    P.append(p)

    C.append(c)

ans = 100000000



for i in range(2 ** D):

    a = 0

    b = 0

    for j in range(D):

        if i >> j & 1:

            a += 100 * P[j] * (j + 1) + C[j]

            b += P[j]

    for k in range(D-1, -1, -1):

        if i >> k & 1:

            continue

        if a >= G:

            break

        for l in range(P[k]):

            a += 100 * (k + 1)

            b += 1

            if a >= G:

                break

    ans = min(ans, b)

print(ans)
"""

bit全探索

"""



D, G = list(map(int, input().split()))

P = []

C = []

for i in range(D):

    p, c = list(map(int, input().split()))

    P.append(p)

    C.append(c)

ans = 100000000



for i in range(2 ** D):

    a = 0

    b = 0

    for j in range(D):

        if i >> j & 1:

            a += 100 * P[j] * (j + 1) + C[j]

            b += P[j]

    for k in range(D-1, -1, -1):

        if i >> k & 1:

            continue

        if a >= G:

            break

        for l in range(P[k] - 1):

            a += 100 * (k + 1)

            b += 1

            if a >= G:

                break

    if a >= G:

        ans = min(ans, b)

print(ans)
D, G = list(map(int, input().split()))
P = []
C = []
for i in range(D):
    p, c = list(map(int, input().split()))
    P.append(p)
    C.append(c)
ans = 100000000
for i in range(2**D):
    a = 0
    b = 0
    for j in range(D):
        if i >> j & 1:
            a += 100 * P[j] * (j + 1) + C[j]
            b += P[j]
    for k in range(D - 1, -1, -1):
        if i >> k & 1:
            continue
        if a >= G:
            break
        for l in range(P[k]):
            a += 100 * (k + 1)
            b += 1
            if a >= G:
                break
    ans = min(ans, b)
print(ans)

"""
bit全探索
"""
D, G = list(map(int, input().split()))
P = []
C = []
for i in range(D):
    p, c = list(map(int, input().split()))
    P.append(p)
    C.append(c)
ans = 100000000
for i in range(2**D):
    a = 0
    b = 0
    for j in range(D):
        if i >> j & 1:
            a += 100 * P[j] * (j + 1) + C[j]
            b += P[j]
    for k in range(D - 1, -1, -1):
        if i >> k & 1:
            continue
        if a >= G:
            break
        for l in range(P[k] - 1):
            a += 100 * (k + 1)
            b += 1
            if a >= G:
                break
    if a >= G:
        ans = min(ans, b)
print(ans)

+""" +bit全探索 +""" -        for l in range(P[k]): +        for l in range(P[k] - 1): -    ans = min(ans, b) +    if a >= G: +        ans = min(ans, b)