Go: package main

import (
        "fmt"
        "bufio"
        "os"
)

func main() {
        var n int
        var a, b string
        sc := bufio.NewScanner(os.Stdin)
        fmt.Scanf("%d", &n)
        for i := 0; i < n; i++ {
                sc.Scan()
                a = sc.Text()
                sc.Scan()
                b = sc.Text()

                if len(a) > len(b) {
                        s := add(a, b)
                        if s[len(a)] > 0 {
                                if len(a) >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i <= len(a);i++ {
                                                fmt.Printf("%d", s[len(a)-i])
                                        }
                                }
                                fmt.Printf("\n")
                        } else {
                                if len(a)-1 >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i < len(a);i++ {
                                                fmt.Printf("%d", s[len(a)-i-1])
                                        }
                                }
                                fmt.Printf("\n")
                        }
                } else {
                        s := add(b, a)
                        if s[len(b)] > 0 {
                                if len(b) >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i <= len(b);i++ {
                                                fmt.Printf("%d", s[len(b)-i])
                                        }
                                }
                                fmt.Printf("\n")
                        } else {
                                if len(b)-1 >= 80 {
                                        fmt.Printf("overflow")
                                } else {
                                        for i := 0; i < len(b);i++ {
                                                fmt.Printf("%d", s[len(b)-i-1])
                                        }
                                }
                                fmt.Printf("\n")
                        }
                }
        }
}

// expects ln > lm
func add(n string, m string) (s [100]int) {
        ln := len(n)
        lm := len(m)
        var sum [100]int

        for i := 0; i < ln; i++ {
                var s, t int
                s = int(n[ln-1-i]) - int('0')

                if lm - 1 - i >= 0 {
                        t = int(m[lm-1-i]) - int('0')
                } else {
                        t = 0
                }

                sum[i+1] = (s + t + sum[i]) / 10
                sum[i] = (s + t + sum[i]) % 10
        }

        return sum
}

Python: import sys
import itertools

dataset_num = int(input())

class Overflow(Exception):
    pass

for _ in range(dataset_num):
    try:
        k1 = input()
        k2 = input()
        k1_val = [0] * 100
        k2_val = [0] * 100

        if len(k1) > 80 or len(k2) > 80:
            raise Overflow()
        
        for i, x in enumerate(reversed(k1)):
            k1_val[i] = int(x)

        for i, x in enumerate(reversed(k2)):
            k2_val[i] = int(x)
        
        res = [0] * 100 
        for i in range(0, 100):
            res[i] += k1_val[i] + k2_val[i]
            if res[i] >= 10:
                res[i+1] += 1
                res[i] -= 10
        sumstr = "".join([str(x) for x in itertools.dropwhile(lambda x: x == 0, reversed(res))])
        if len(sumstr) > 80:
            raise Overflow()

        print(sumstr)
    except Overflow:
        print("overflow")

Python: import math

n = int(input())
for i in range(n):
    for i in range(2):
        x = int(input())
        y = int(input())
        result = x + y
        print(result) if math.log10(result) + 1 < 80 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")
    else:
        print(result)

Python: #!/usr/bin/python
# AOJ
# 0015

for i in range(int(input())):
    n1 = list(input())
    n2 = list(input())
    if len(n2) > len(n1):
        n1, n2 = n2, n1

    ans = []
    for i in range(len(n1)):
        a = int(ans.pop(0)) if len(ans) == i + 1 else 0
        c1 = int(n1.pop(-1))
        c2 = int(n2.pop(-1)) if len(n2) != 0 else 0
        ans = list(str(a + c1 + c2)) + ans
    if len(ans) > 80:
        print('overflow')
    else:
        print(''.join(ans))

Python: n=int(input())
for i in range(n):
    a,b=[int(input()) for _ in range(2)]
    print("overflow" if len(str(a+b))>80 else a+b)

Python: while True:
    try:
        N=int(input())
        for i in range(N):
            a=input()
            b=input()
            if len(a)>80 or len(b)>80:
                print("overflow")
            else:
                a=int(a)
                b=int(b)
                s=a+b
                if len(str(s))>80:
                    print("overflow")
                else:
                    print(s)
    except:break

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: n = int(input())

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

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)