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: 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")