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#include<iostream>
#include<string>
#include<stdio.h>
using namespace std;
char a[502],b[502];
int s[502],c[501],d[501];
int main()
{
    int i,j,o;
    i=1,j=1;
    cin>>a[1];
    while(a[i]!='\n')
    {   
        i++;   
        a[i]=getchar();
        if(a[i-1]!='\n')
        {
            int g=a[i-1]-48;
            c[i-1]=g;
        }
    }
    cin>>b[1];
    while(b[j]!='\n')
    {
        j++;
        b[j]=getchar();
        if(b[j-1]!='\n')
        {
            int g=b[j-1]-48;
            d[j-1]=g;
        }
    }
    int m=501-i;
    int n=501-j;
    for(int p=i-1;p>=1;p--)
        c[p+m]=c[p];
    for(int p=j-1;p>=1;p--)
        d[p+n]=d[p];
    int l=m<n?m:n;
    for(int i=500;i>l;i--)
    {
        s[i+1]+=c[i]+d[i];
        if(s[i+1]>=10)
        {
            s[i+1]-=10;
            s[i]++;
        }
    }
    for(o=1;o<=501;o++)
        if(s[o]!=0) break;
    if(o==502) cout<<"0";
    for(int k=o;k<=501;k++)
        cout<<s[k];
    cout<<endl;
    return 0;
}

Thanks.