Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(100000000000000)

def answer():
    input = sys.stdin.readline
    M = int(input())

    part = ''
    for i in range(M):
        d, c = input().split()
        part += d * int(c)

    _round = 0
    while len(part) > 1:
        _round += 1
        # 和10以上を探索
        mt10 = 0
        for i in range(1, len(part)):
            s1 = part[-i]
            s2 = part[-i-1]
            if int(s1) + int(s2) >= 10:
                mt10 = - i - 1
                break

        if mt10 == 0:
            s1 = part[0]
            s2 = part[1]
            s3 = part[2:]
            part = str(int(s1) + int(s2)) + s3
        else:
            s1 = part[:mt10]
            s2 = part[mt10]
            s3 = part[mt10+1]
            s4 = ''
            if mt10 < -2:
                s4 = part[mt10+2:]
            part = s1 + str(int(s2)+int(s3)) + s4

    print(_round)


if __name__ == '__main__':
    answer()


Fixed submission:
import sys

def answer():
    input = sys.stdin.readline
    M = int(input())

    Ds = [0] * M
    Cs = [0] * M
    total = 0

    for i in range(M):
        c, d = map(int, input().split())
        Cs[i] = c
        Ds[i] = d
        total += d * c

    digits = sum(Ds)

    ans = (digits-1) + (total-1) // 9

    print(ans)


if __name__ == '__main__':
    answer()

Buggy python submission (verdict: Runtime Error):
import sys
sys.setrecursionlimit(1000000000)

def answer():
    input = sys.stdin.readline
    M = int(input())

    part = ''
    for i in range(M):
        d, c = input().split()
        part += d * int(c)

    _round = 0
    while len(part) > 1:
        _round += 1
        # 和10以上を探索
        mt10 = 0
        for i in range(1, len(part)):
            s1 = part[-i]
            s2 = part[-i-1]
            if int(s1) + int(s2) >= 10:
                mt10 = - i - 1
                break

        if mt10 == 0:
            s1 = part[0]
            s2 = part[1]
            s3 = part[2:]
            part = str(int(s1) + int(s2)) + s3
        else:
            s1 = part[:mt10]
            s2 = part[mt10]
            s3 = part[mt10+1]
            s4 = ''
            if mt10 < -2:
                s4 = part[mt10+2:]
            part = s1 + str(int(s2)+int(s3)) + s4

    print(_round)


if __name__ == '__main__':
    answer()


Fixed submission:
import sys

def answer():
    input = sys.stdin.readline
    M = int(input())

    Ds = [0] * M
    Cs = [0] * M
    total = 0

    for i in range(M):
        c, d = map(int, input().split())
        Cs[i] = c
        Ds[i] = d
        total += d * c

    digits = sum(Ds)

    ans = (digits-1) + (total-1) // 9

    print(ans)


if __name__ == '__main__':
    answer()

Buggy python submission (verdict: Runtime Error):
import sys

def answer():
    input = sys.stdin.readline
    M = int(input())

    part = ''
    for i in range(M):
        d, c = input().split()
        part += d * int(c)

    _round = 0
    while len(part) > 1:
        _round += 1
        # 和10以上を探索
        mt10 = 0
        for i in range(1, len(part)):
            s1 = part[-i]
            s2 = part[-i-1]
            if int(s1) + int(s2) >= 10:
                mt10 = - i - 1
                break

        if mt10 == 0:
            s1 = part[0]
            s2 = part[1]
            s3 = part[2:]
            part = str(int(s1) + int(s2)) + s3
        else:
            s1 = part[:mt10]
            s2 = part[mt10]
            s3 = part[mt10+1]
            s4 = ''
            if mt10 < -2:
                s4 = part[mt10+2:]
            part = s1 + str(int(s2)+int(s3)) + s4

    print(_round)


if __name__ == '__main__':
    answer()


Fixed submission:
import sys

def answer():
    input = sys.stdin.readline
    M = int(input())

    Ds = [0] * M
    Cs = [0] * M
    total = 0

    for i in range(M):
        c, d = map(int, input().split())
        Cs[i] = c
        Ds[i] = d
        total += d * c

    digits = sum(Ds)

    ans = (digits-1) + (total-1) // 9

    print(ans)


if __name__ == '__main__':
    answer()

Buggy python submission (verdict: Runtime Error):
def answer():
    input = sys.stdin.readline
    M = int(input())

    part = ''
    for i in range(M):
        d, c = input().split()
        part += d * int(c)

    _round = 0
    while len(part) > 1:
        _round += 1
        # 和10以上を探索
        mt10 = 0
        for i in range(1, len(part)):
            s1 = part[-i]
            s2 = part[-i-1]
            if int(s1) + int(s2) >= 10:
                mt10 = - i - 1
                break

        if mt10 == 0:
            s1 = part[0]
            s2 = part[1]
            s3 = part[2:]
            part = str(int(s1) + int(s2)) + s3
        else:
            s1 = part[:mt10]
            s2 = part[mt10]
            s3 = part[mt10+1]
            s4 = ''
            if mt10 < -2:
                s4 = part[mt10+2:]
            part = s1 + str(int(s2)+int(s3)) + s4

    print(_round)


if __name__ == '__main__':
    answer()


Fixed submission:
import sys

def answer():
    input = sys.stdin.readline
    M = int(input())

    Ds = [0] * M
    Cs = [0] * M
    total = 0

    for i in range(M):
        c, d = map(int, input().split())
        Cs[i] = c
        Ds[i] = d
        total += d * c

    digits = sum(Ds)

    ans = (digits-1) + (total-1) // 9

    print(ans)


if __name__ == '__main__':
    answer()