teste de subtração

#include <iostream>

using namespace std;

int main(){
    int a[2020];
    int b[2021];

    a[0] = 5;
    a[1]= 2;
    a[2]= 5;
    a[3]= 0;

    b[0]=3;
    b[1]=2;
    b[2]=8;
    b[3]=1;

    /*for(int i = 0; i <3; i++){
        a[i] = i+1;
        b[i] = 3-i;
    }

    for(int i = 0; i <3; i++){
       cout<< a[i];

    }

    cout<<"\n";

    for(int i = 0; i <3; i++){
       cout<< b[i];

    }*/

    cout<<"\n";

    if(a[3] == 0 || b[3]==1){
         for (int i =2;  i>=0 ; i--){
                        a[i]=a[i]-b[i];

                        if(a[i]<0){
                            a[i] = a[i]+10;
                            a[i-1] = a[i-1]-1;
                        }



        }

    }

    for(int i = 0; i<3;i++){
        cout<<a[i]<<" ";
    }
}