1
#include <iostream>
using namespace std;
int main(){
int s=0, t;
do{
cin>>t;
s=s+t;
}while(t!=0);
cout<<s;
}
2
#include <iostream>
using namespace std;
int main(){
int n,i,j;
char c,d;
cin>>n>>c>>d;
for(i=0;i<n;i++){
for(j=0;j<n;j++)if((i+j)%2!=1)cout<<c; else cout<<d;
cout<<endl;
}
}