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: 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")

Python: # National Budget
md = 80
for _ in range(int(input())):
    a,b = int(input()),int(input())
    ab = a + b
    if a >= pow(10,md) or b >= pow(10,md) or ab >= pow(10,md):
        print('overflow')
    else:
        print(a+b)

Python: num = int(input())

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

Python: for i in range(int(input())):
    try:
        a = int32(sum([int32(j) for j in input().split()]))
    except:
        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(s)
    else:
        print('overflow')

Python: n = int(input())
for i in range(n):
    x = input()
    y = input()
    if len(x) > 80 or len(y) > 80:
        print("overflow")
        continue
    s = ""
    rx = x[::-1]
    ry = y[::-1]
    lx = len(x)
    ly = len(y)
    if lx > ly:
        ml = lx
    else:
        ml = ly
    c = 0
    for j in range(ml + 1):
        x1 = 0
        y1 = 0
        if j < lx:
            x1 = int(rx[j])
        if j < ly:
            y1 = int(ry[j])
        c1 = x1 + y1 + c
        s += str(c1 % 10)
        c = c1 // 10

    rs = s[::-1]
    result = ""
    for j in range(len(rs)):
        if rs[j] != "0":
            result = rs[j:]
            break

    if len(result) > 80:
        print("overflow")
    elif result == "":
        print(0)
    else:
        print(result)

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) else 'overflow ')

Python: import math

def calc_digit(data1, data2):
    if(data1 == 0):
        data_size2 = int(len(str(data2)))
        data_size1 = 1
    elif(data2 == 0):
        data_size1 = int(len(str(data2)))
        data_size2 = 1
    else:
        data_size1 = int(len(str(data1)))
        data_size2 = int(len(str(data2)))
    return(data_size1, data_size2)

def two_number_sum(data1, data2):
    result = data1 + data2
    if int(len(str(result))) > 80:
        print("overflow")
    else:
        print(result)

def main():
    a = []
    N = int(input())
    for i in range(N*2):
        a.append(input())
    for i in range(0, N*2):
        if i % 2 == 0:
            continue
        else:
            data1 = int(a[i-1])
            data2 = int(a[i])
            if(data1 == None):
                data1 = 0
            elif(data2 == None):
                data2 = 0
            x, y = calc_digit(data1, data2)
            if(x > 80 or y > 80):
                print("overflow")
                continue
            two_number_sum(data1, data2)

if __name__ == '__main__':
    main()

Python: import sys
import re
def line():return sys.stdin.readline().strip()

N = input()
while True:
    try:
        a = int(line())
        b = int(line())
        if a + b >= 10 ** 80:
            print("overflow")
        else:
            print(a + b)
    except:
        break

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

Python: N = int(input())
for _ in range(N):
    a = int(input())
    b = int(input())
    c = a + b
    length = len(str(c))
    print([c, "overflow"][length > 80])

Python: 
if __name__ == '__main__':
    n = (int)(input())
    for _ in range(n):
        sNumber = (int)(input())
        tNumber = (int)(input())
        uNumber = sNumber+tNumber
        print("over flow" if uNumber >= 10**80 else uNumber)

Python: def Add(numa, numb):
	longer = (numa if len(numa) >= len(numb) else numb)
	shorter = (numa if len(numa) < len(numb) else numb)
	carry = 0
	result = ''
	for s in range(-1, -len(shorter) - 1, -1):
		ans = int(longer[s]) + int(shorter[s]) + carry
		if ans >= 10:
			result = str(ans % 10) + result
			carry = 1
		else:
			result = str(ans) + result
			carry = 0
	for l in range(-len(shorter) - 1, -len(longer) - 1, -1):
		ans = int(longer[l]) + carry
		if ans >= 10:
			result = str(ans % 10) + result
			carry = 1
		else:
			result = str(ans) + result
			carry = 0
	return (result if carry == 0 else '1' + result)

N = eval(input())
for _ in range(N):
	a = input()
	b = input()
	ans = Add(a, b)
	print('overflow' if len(a) >= 80 or len(b) >= 80 or len(ans) >= 80 else ans)

Python: n = int(input())

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

    print(a + b)

Python: N=int(input())
A=[]
B=[]
for i in range(N):
    a = int(input())
    b = int(input())
    A.append(a)
    B.append(b)

for i in range(N):
    if A[i] >= 10 ** 79 or B[i] >= 10 ** 79:
        print("overflow")
    elif A[i] + B[i]>= 10 ** 79:
        print("overflow")
    else:
        print(A[i]+B[i])

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) else 'overflow')

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