Go: package main

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

var sc = bufio.NewScanner(os.Stdin)

func main() {
	sc.Scan()
	dataset, _ := strconv.Atoi(sc.Text())
	var firstdata *big.Int

	for i := 0; i < dataset*2; i++ {
		n := new(big.Int)
		sc.Scan()
		data, _ := n.SetString(sc.Text(), 10)

		if i%2 == 0 {
			firstdata = data
			continue
		}

		result := new(big.Int)
		if result := result.Add(data, firstdata); len(result.String()) > 80 {
			fmt.Println("overflow")
			continue
		} else {
			fmt.Println(result)
		}
	}
}

Python: def largeBudget(a, b):
  if a > 1e+80 or b > 1e+80: print("overflow")
  elif a+b > 1e+80: print("overflow")
  else: print("%d"%(a+b))

N = int(input())
for i in range(N):
  a = int(input())
  b = int(input())
  largeBudget(a, b)

Python: times=int(input())
for i in range(times):
    a=int(input())
    b=int(input())
    if len(str(a))<80 and len(str(b))<80 and len(str(a+b))<80:
        print(a+b)
    else: print("overflow")

Python: n = int(input())
for _ in range(n):
    a, b = input(), input()
    m = abs(len(a) - len(b))
    if len(a) > len(b):
        a = '0' + a
        b = '0' * (m+1) + b
    else:
        a = '0' * m + a
        b = '0' + b
    a, b = a[::-1], b[::-1]
    
    budget = []
    flag = False
    for i in range(0, len(a), 10):
        t = int(a[i:i+10][::-1]) + int(b[i:i+10][::-1]) 
        if flag: t += 1
        t = str(t)

        if len(t) > 10:
            t = t[1:]
            flag = True
        elif i + 10 < len(a):
            t = '0' * abs(len(t) - 10) + t
            flag = False
        else:
            flag = False
        budget.append(t)
    
    print(''.join(budget[::-1]))

Python: import math
c  = raw_input();
for var in range(0, int(c)) :
	n1 = raw_input();
	n2 = raw_input();
	sum = int(n1) + int(n2)
	if int(math.log10(sum)) + 1 > 80 :
		print("overflow")
	else :
		print(sum)
exit(0)

Python: N = int(input())
num = [sum([int(input()) for _ in range(2)]) for _ in range(N)]

for n in num:
    if n < 10**80:
        print(n)
    else:
        print('overflow')

Python: n = int(input())
for _ in range(n):
    s1 = int(input())
    s2 = int(input())
    s3 = s1+s2
    if len(str(s3)) > 80:
        print("overflow")
    else:
        print(s3)

Python: from math import log10
n = int(input())
for i in range(n):
    a = int(input())
    b = int(input())
    c = a+b
    if (log10(c) > 80):
        print("overflow")
    else:
        print(c)

Python: import math
c  = raw_input()
for var in range(0, int(c)) :
	n1 = raw_input();
	n2 = raw_input();
	sum = int(n1) + int(n2)
	if int(math.log10(sum)) + 1 > 80 :
		print("overflow")
	else :
		print(sum)

Python: n=int(input())
for i in range(n):
	a=int(input())
	b=int(input())
	print(a+b)

Python: import math

c  = raw_input()

for var in range(0, int(c)) :
	n1 = raw_input()
	n2 = raw_input()
	sum = int(n1) + int(n2)

	if int(math.log10(sum)) + 1 > 80 :
		print("overflow")
	else :
		print(sum)

Python: times=int(input())
for i in range(times):
    a=int(input())
    b=int(input())
    if int((a+b)/(1e80))!=0:
        print("overflow")
    else: print(a+b)

Python: n = int(input())

for i in range(0, n):
    a = int(input())
    b = int(input())
    if len(str(a + b)) >= 80:
        print("overflow")
    elif len(str(a)) >= 80:
        print("overflow")
    elif len(str(b)) >= 80:
        print("overflow")
    else :
        print(a + b)

Python: import math
c  = raw_input();
for var in range(0, int(c)) :
	n1 = raw_input();
	n2 = raw_input();
	sum = int(n1) + int(n2)
	if int(math.log10(sum)) + 1 > 80 :
		print("overflow")
	else :
		print(sum)
exit()

Python: if __name__ == "__main__":
    nset = int(input())

    for i in range(0, nset):
        sa = input()
        sb = input()
        a = int(sa)
        b = int(sb)
        c = a + b

        if len(sa) > 80 or len(sb) > 80 or len(str(c)) > 80:
            print("overflow")
        else:
            print(c)

Python: for i in range(int(input())):
    s=int(input())+int(input())
    if s>=int("1"+"0"*80):
        print("overflow")
    else:
        print(s)

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

def main():
    for i in range(int(input())):
        a=str(int(input())+int(input()))
        if len(a)>80:
            print("overflow")
            break
        print(a)
            
    
if __name__ == '__main__':
    main()

Python: n = int(input())

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

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

Python: N = int(input())
import re
for _ in [0]*N:
    a = input().zfill(100)
    b = input().zfill(100)
    result = []
    prev = 0
    for i in range(1, 81):
        n = int(a[-i]) + int(b[-i]) + prev
        result.append(n%10)
        prev = n // 10
    if int(a[-81]) + int(b[-81]) + prev > 0 or int(a[:20]) + int(b[:20]) > 0:
        print("overflow")
    else:
        print(re.sub(r"^0+", "", "".join(map(str, result[::-1]))))

Python: n=int(input())
for i in range(n):
    a=input()
    if a==1:
        break
    b=input()
    print(str(a)+str(b))

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: 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")
    elif math.log10(a) + 1 > 80 :
        print("overflow")
    elif math.log10(b) + 1 > 80 :
        print("overflow")
    else :
        print(a + b)

Python: for _ in range(int(input())):
    a=int(input())+int(input())
    print(a if a<10**80else'overflow')

Python: upper = 10**81
n = int(input())
for i in range(n):
    n1 = int(input())
    n2 = int(input())
    if n1 >= upper or n2 >= upper:
        print("overflow")
        continue
    print( n1 + n2 if n1+n2 < upper else "overflow")

Python: l = int(input())
for i in range(l):
    a = int(input()) + int(input())
    if(a > 1E80):
        print('overflow')
    else:
        print(a)

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行の入力（Nが最初の行）
n = int(input())
for _ in range(n):
    m1, m2 = int(input()), int(input())
    print(m1 + m2 if len(str(m1 + m2)) <= 80 else 'overflow')

Python: # coding: utf-8

n = int(raw_input())

for i in range(n):
	n1 = int(raw_input())
	n2 = int(raw_input())
	sum = n1 + n2
	strsum = str(sum)
	if len(strsum) > 80:
		print("overflow")
	else:
		print(strsum)

Python: # Aizu Problem 0015: National Budget
#
import sys, math, os

# read input:
PYDEV = os.environ.get('PYDEV')
if PYDEV=="True":
    sys.stdin = open("sample-input.txt", "rt")


N = int(input())
for n in range(N):
    a = int(input())
    b = int(input())
    budget = a + b
    print(budget if len(str(budget)) <= 80 else "overflow")

Python: times=int(input())
for i in range(times):
    a=int(input())
    b=int(input())
    if len(str(a))<80 or len(str(b))<80 or len(str(a+b))<80:
        print(a+b)
    else: print("overflow")

Python: for i in range(int(input())):
    a, b = int(input()), int(input())
    result = a+b if len(str(a+b))<=80 else 'overflow'
    print(result)

Python: for _ in range(int(input())):
    a = int(input())
    b = int(input())
    s = a + b
    if s >= 10 ** 80:
        print('overflow')
    else:
        print(s)

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

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