#include<bits/stdc++.h> using namespace std; string a1,b1,c1; int a[105],b[105],s[105],lena,lenb,lenc,lens,n; int main(){ cin>>n; b1=c1=""; lenb=b1.length(); lenc=c1.length(); for(int i=1;i<=n;i++){ cin>>a1; lena=a1.length(); if(!lenc||lena<lenc||lena==lenc&&a1<c1){ c1=a1; lenc=lena; } if(lenb<lena||lenb==lena&&b1<a1){ b1=a1; lenb=lena; } } for(int i=1;i<=lenb;i++)a[i]=b1[lenb-i]-48; for(int i=1;i<=lenc;i++)b[i]=c1[lenc-i]-48; lens=lenb; for(int i=1;i<=lens;i++){ if(a[i]<b[i]){ a[i+1]--; a[i]+=10; } s[i]=a[i]-b[i]; } while(!s[lens]&&lens>1)lens--; for(int i=lens;i>=1;i--)cout<<s[i]; return 0; }