Go: package main

import (
	"bufio"
	"fmt"
	"math/big"
	"os"
	"strconv"
)

var scanner = bufio.NewScanner(os.Stdin)

func nextString() string {
	scanner.Scan()
	return scanner.Text()
}

func nextInt() int {
	n, err := strconv.Atoi(nextString())
	if err != nil {
		fmt.Printf("strconv.Atoi failed: %v\n", err)
	}
	return n
}

func main() {
	scanner.Split(bufio.ScanWords)

	const maxCapacity = 512 * 1024
	buf := make([]byte, maxCapacity)
	scanner.Buffer(buf, maxCapacity)

	n := nextInt()
	maxint, _ := new(big.Int).SetString("100000000000000000000000000000000000000000000000000000000000000000000000000000000", 10)

	for i := 0; i < n; i++ {
		aStr := nextString()
		bStr := nextString()

		a, _ := new(big.Int).SetString(aStr, 10)
		b, _ := new(big.Int).SetString(bStr, 10)
		c := big.NewInt(0).Add(a, b)

		if c.Cmp(maxint) < 0 {
			fmt.Println(c)
		} else {
			fmt.Println("overflow")
		}
	}
}

Python: # AOJ 0015 National Budget
# Python3 2018.6.9 bal4u

n = int(input())
for i in range(n):
    a = str(input())
    b = str(input())
    if len(a) > 80 or len(b) > 80:
        print('overflow')
    else:
        s = str(int(a)+int(b))
        if len(s) <= 80:
            print(s)
        else:
            print('overflow')

Python: #!/usr/bin/env python
#-*- coding:utf-8 -*-

import sys
import math

n = int(input())

for _ in range(n):
    x = int(input())
    y = int(input())
    print(x+y)

Python: n = int(input())
for i in range(n):
  a = int(input())
  b = int(input())
  c = a + b
  if len(str(c)) > 80:
    print("overflow")
  else:
    print(c)

Python: for i in range(int(input())):
    a = int(input())
    b = int(input())
    if a + b > 2147483647:
        print("overflow")
    else:
        print(a)

Python: n=int(input())
ans_list=[]

for i in range(n):
	a=int(input())
	b=int(input())
	c=a+b
	if max(a,b,c)>=10**80:
		ans_list.append("overflow")
	else:
		ans_list.append(c)

for i in ans_list:
	print(i)

Python: import heapq
from collections import deque
from enum import Enum
import sys
import math
from _heapq import heappush, heappop
import copy

BIG_NUM = 2000000000
HUGE_NUM = 99999999999999999
MOD = 1000000007
EPS = 0.000000001
sys.setrecursionlimit(100000)


num_query = int(input())

for _ in range(num_query):
    A = list(map(int,input()))
    B = list(map(int,input()))

    if len(A) > 80 or len(B) > 80:
        print("overflow")
        continue

    if len(B) > len(A): #len(B) <= len(A)にする
        A,B = B,A
    A.reverse()
    B.reverse()

    ANS = deque()
    add = 0

    for digit in range(len(A)):
        if digit >= len(B):
            tmp = add+A[digit]
            add = tmp//10
            ANS.append(tmp%10)
        else:
            tmp = add+B[digit]+A[digit]
            add = tmp//10
            ANS.append(tmp%10)

    if len(A) == 80 and add == 1:
        print("overflow")
    else:
        if add == 1:
            ANS.append(1)

        while len(ANS) > 0:
            print("%d"%(ANS.pop()),end="")
        print()

Python: # -*- coding: utf-8 -*-
import math

n=int(input())

for i in range(n):
    a=int(input())
    b=int(input())
    st=str(a+b)
    if len(st)>80:
        print("overflow")
    else:
        print(st)

Python: import math

N = int(input())
for i in range(N):
    a = int(input())
    b = int(input())
    if a >= 10**79 or b >= 10 ** 79 or a + b >= 10 ** 79:
        print("overflow")
    else:
        print(a + b)

Python: from functools import reduce
from operator import add
num = int(input())
for _ in range(num):
    budget = reduce(add, [int(input()) for _ in range(2)])
    if len(str(budget)) > 80:
        print('overflow')
    else:
        print(budget)

Python: from decimal import Decimal


n = int(input())
for _ in range(n):
    a = Decimal(input())
    b = Decimal(input())
    s = a + b
    s = str(s)
    if len(s) >= 80:
        print("overflow")
    else:
        print(s)

Python: import sys
f = sys.stdin
n = int(f.readline())
for _ in range(n):
    a = f.readline().strip()
    b = f.readline().strip()
    c = int(a) + int(b)
    c = '{}'.format(c)
    print(c if len(c) <= 80 else 'overflow')

Python: n = int(input())
for _ in range(n):
    a = sum([int(input()) for _ in range(2)])
    print(a if a < 10**80 else 'overflow')

Python: import math

n = int(input())
for i in range(0, n) :
    a = int(input())
    b = int(input())
    if (math.log10(a + b) + 1 > 80) :
        print("overflow")
        continue
    print(a + b)

Python: n = int(input())
for i in range(n):
	s = int(input())+int(input())
	if len(str(s))>80:
		print("overflow")
	else:
		print(s)

Python: n=int(input())

for i in range(n):
    a=int(input())
    b=int(input())
    c=a+b
    ss=str(c)
    if len(ss)>80:
        print("overflow")
    else:
        print(ss)

Python: n=int(input())
ans_list=[]

for i in range(n):
	a=int(input())
	b=int(input())
	if max(a,b,a+b)>=10**80:
		ans_list.append("overflow")
	else:
		ans_list.append(a+b)

for i in ans_list:
	print(i)

Python: if __name__ == '__main__':
    N = int(input())
    for _ in range(N):
        a = input()
        b = input()
        c = str(int(a) + int(b))
        if len(a) > 80 or len(b) > 80 or len(c) > 80:
            print("overflow")
        else:
            print(c)

Python: import math

def main() :
    n = int(input())
    for i in range(0, n) :
        a = int(input())
        b = int(input())
        if (math.log10(a + b) + 1 > 80) :
            print("overflow")
            continue
        print(a + b)

main()

Python: n = int(input())
for i in range(n):
	a = int(input())
	b = int(input())
	
	if (a+b) < (10**80):
		print(a+b)
	else:
		print("overflow")

Python: import math

n = int(input())

for i in range(0, n):
    a = int(input())
    b = int(input())
    if math.log10(a + b) + 1 > 80:
        print("overflow")
    else :
        print(a + b)

Python: import math

N = int(input())
for i in range(N):
    a = int(input())
    b = int(input())
    if math.log10(a) > 79 or math.log10(b) > 79 or math.log10(a + b) > 79:
        print("overflow")
    else:
        print(a + b)

Python: '''
Created on Mar 21, 2013

@author: wukc
'''

from sys import stdin

n=int(stdin.readline())
for i in range(n):
    a,b=[stdin.readline().strip().lstrip("0") for k in range(2)]
    if len(a)>80 or len(b)>80:
        print("overflow")
        continue
    a,b=a.rjust(len(b),'0'),b.rjust(len(a),'0')
    ans=[]
    c=0
    for x,y in zip(a[::-1],b[::-1]):
        t=int(x)+int(y)+c
        c=t//10
        ans+=[t%10]
    ans+=[c]
    ans="".join(map(str,ans[::-1])).lstrip("0")
    if len(ans)>80:
        print("overflow")
        continue
    print(ans.rjust(1,'0'))

Python: # -*- coding:utf-8 -*-

def main():
    LIST=[]
    for i in range(int(input())):
        a=int(input())
        b=int(input())
        LIST.append(a+b)

        if len(LIST)>80:
            print("overflow")
            break

    for v in LIST:
        print(v)
            
    
if __name__ == '__main__':
    main()

Python: n=int(input())
A=[]
while True:
	try:
		x=int(input())
		A.append(x)
	except EOFError:
		break
start=0
end=start+n
for i in range(len(A)//n):
	print(sum(A[start:end]))
	start+=n
	end+=n

Python: '''
Created on Mar 21, 2013

@author: wukc
'''

from sys import stdin

n=int(stdin.readline())
for i in range(n):
    a,b=[stdin.readline().strip().lstrip("0") for k in range(2)]
    if len(a)>80 or len(b)>80:
        print("overflow")
        continue
    a,b=a.rjust(len(b),'0'),b.rjust(len(a),'0')
    ans=[]
    c=0
    for x,y in zip(a[::-1],b[::-1]):
        t=int(x)+int(y)+c
        c=t//10
        ans+=[t%10]
    ans+=[c]
    ans="".join(map(str,ans[::-1])).lstrip("0")
    if len(ans)>80:
        print("overflow")
        continue
    print(ans)

Python: for x in range(input()):
    x = input() + input()
    print("{:.80g}".format(x) if x < 1E79 else "overflow")