#include<bits/stdc++.h> #define MAXN 1000011 #define int long long usingnamespace std; inlineintread(){ int x=0,f=1; char ch=getchar(); while (ch<'0'||ch>'9'){ if (ch=='-') f=-1; ch=getchar(); } while (ch>='0'&&ch<='9'){ x=(x<<3)+(x<<1)+(ch^'0'); ch=getchar(); } return x*f; } int a[MAXN],b[MAXN]; #undef int intmain(){ #define int long long srand(19260817); int n=read(); for (registerint i=1;i<=n;++i){ a[i]=read(); } for (registerint i=1;i<=n;++i){ b[i]=i; } for (registerint t=1;t<=100000;++t){ random_shuffle(b+1,b+1+n); int sum=0; for (registerint i=1;i<=n;++i){ sum+=a[b[i]]; if (sum%n==0){ for (registerint j=1;j<=i;++j){ printf("%lld %lld\n",b[j],a[b[j]]); } printf("\n"); return0; } } } }