C :

#include <stdio.h>
#include <stdlib.h>
#include <string.h>
#define maxn 210

typedef struct bign{
int a[maxn];
int len;
}bign;

bign change(char s[]){
bign c;
c.len=0;
memset(c.a,0,sizeof(c.a));
int len = strlen(s);
for(int i = 0;i < len; i++)c.a[c.len++] = s[len-1-i] - 48;
return c;
}

bign proc(bign A, bign B) {
bign C;
C.len = 0;
memset(C.a,0,sizeof(C.a));
for(int i = 0;i < A.len || i < B.len; i++) {
    if(A.a[i] < B.a[i]) {
        A.a[i+1]--;
        A.a[i] += 10;
    }
    C.a[C.len++] = A.a[i] - B.a[i];
}
while(C.len - 1 >= 1 && C.a[C.len-1] == 0) {
    C.len--;
}
return C;
}

int biger(bign A, bign B) {
if(A.len>B.len)return 1;
if(A.len<B.len) return 0;
for(int i = A.len-1;i >= 0; i--) {
    if(A.a[i]<B.a[i])return 0;
}
return 1;
}

int main()
{
    char a[maxn], b[maxn];
    while(scanf("%s %s",a,b) != EOF) {
        bign A = change(a);
        bign B = change(b);
        if(biger(A,B)){
            bign ans = proc(A,B);
            for(int i = ans.len-1;i >= 0; i--){
                printf("%d",ans.a[i]);
            }
            printf("\n");
            continue;
        }
        bign ans = proc(B,A);
        printf("-");
        for(int i = ans.len-1;i >= 0;i--)printf("%d",ans.a[i]);
        printf("\n");
    }
    return 0;
}

C++ :

#include<iostream>
using namespace std;
string a,b,c,fh;
int a1[256],a2[256],x,y,z,u;
int main()
{
    cin>>a>>b;
    x=a.length()-1;
    y=b.length()-1;
    if ((y>x) || ((y==x) && (b>a))) 
    {
         fh='-';
         c=a;a=b;b=c;
         u=y;y=x;x=u;
    } 
    for (z=0;z<=x;z++) a1[x-z]=a[z]-'0';
    for (z=0;z<=y;z++) a2[y-z]=b[z]-'0';
    if (a==b) cout<<"0";
    else 
    {
         for (z=0;z<=y;z++) 
              {
                   a1[z+1]=a1[z+1]-1;
                   a1[z]=a1[z]+10-a2[z];
                   a1[z+1]=a1[z+1]+(a1[z]/10);
                   a1[z]=a1[z]%10;
              }
         u=x;
         while (a1[u]==0) {u--;}
         cout<<fh;
         for (z=u;z>=0;z--) cout<<a1[z];
         }
    //system("pause");
    return 0;
}

Java :

import java.math.BigInteger;
import java.util.Scanner;

public class Main {
	public static void main(String[] args) {
		Scanner cin =new Scanner(System.in);
		BigInteger a,b,c;
		a=cin.nextBigInteger();
		b=cin.nextBigInteger();
		c=a.subtract(b);
		System.out.println(c);
	}
}

Python :

# coding=utf-8
s=eval(input())
t=eval(input())
print(s-t)