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 #include <bits/stdc++.h>
#define MAXN 9999 #define MAXSIZE 10 #define DLEN 4
class BigNum { private: int a[10000]; int len; public: BigNum(){ len = 1;memset(a,0,sizeof(a)); } BigNum(const int); BigNum(const char*); BigNum(const BigNum &); BigNum &operator=(const BigNum &);
friend std::istream& operator>>(std::istream&, BigNum&); friend std::ostream& operator<<(std::ostream&, BigNum&);
BigNum operator+(const BigNum &) const; BigNum operator(const BigNum &) const; BigNum operator*(const BigNum &) const; BigNum operator/(const int &) const;
BigNum operator^(const int &) const; int operator%(const int &) const; bool operator>(const BigNum & T)const; bool operator>(const int & t)const; }; BigNum::BigNum(const int b) { int c,d = b; len = 0; memset(a,0,sizeof(a)); while(d > MAXN) { c = d  (d / (MAXN + 1)) * (MAXN + 1); d = d / (MAXN + 1); a[len++] = c; } a[len++] = d; } BigNum::BigNum(const char*s) { int t,k,index,l,i; memset(a,0,sizeof(a)); l=strlen(s); len=l/DLEN; if(l%DLEN) len++; index=0; for(i=l1;i>=0;i=DLEN) { t=0; k=iDLEN+1; if(k<0) k=0; for(int j=k;j<=i;j++) t=t*10+s[j]'0'; a[index++]=t; } } BigNum::BigNum(const BigNum & T) : len(T.len) { int i; memset(a,0,sizeof(a)); for(i = 0 ; i < len ; i++) a[i] = T.a[i]; } BigNum & BigNum::operator=(const BigNum & n) { int i; len = n.len; memset(a,0,sizeof(a)); for(i = 0 ; i < len ; i++) a[i] = n.a[i]; return *this; } std::istream& operator>>(std::istream & in, BigNum & b) { char ch[MAXSIZE*4]; int i = 1; in>>ch; int l=strlen(ch); int count=0,sum=0; for(i=l1;i>=0;) { sum = 0; int t=1; for(int j=0;j<4&&i>=0;j++,i,t*=10) { sum+=(ch[i]'0')*t; } b.a[count]=sum; count++; } b.len =count++; return in;
} std::ostream& operator<<(std::ostream& out, BigNum& b) { int i; out << b.a[b.len  1]; for(i = b.len  2 ; i >= 0 ; i) { out.width(DLEN); out.fill('0'); out << b.a[i]; } return out; }
BigNum BigNum::operator+(const BigNum & T) const { BigNum t(*this); int i,big; big = T.len > len ? T.len : len; for(i = 0 ; i < big ; i++) { t.a[i] +=T.a[i]; if(t.a[i] > MAXN) { t.a[i + 1]++; t.a[i] =MAXN+1; } } if(t.a[big] != 0) t.len = big + 1; else t.len = big; return t; } BigNum BigNum::operator(const BigNum & T) const { int i,j,big; bool flag; BigNum t1,t2; if(*this>T) { t1=*this; t2=T; flag=0; } else { t1=T; t2=*this; flag=1; } big=t1.len; for(i = 0 ; i < big ; i++) { if(t1.a[i] < t2.a[i]) { j = i + 1; while(t1.a[j] == 0) j++; t1.a[j]; while(j > i) t1.a[j] += MAXN; t1.a[i] += MAXN + 1  t2.a[i]; } else t1.a[i] = t2.a[i]; } t1.len = big; while(t1.a[t1.len  1] == 0 && t1.len > 1) { t1.len; big; } if(flag) t1.a[big1]=0t1.a[big1]; return t1; }
BigNum BigNum::operator*(const BigNum & T) const { BigNum ret; int i,j,up; int temp,temp1; for(i = 0 ; i < len ; i++) { up = 0; for(j = 0 ; j < T.len ; j++) { temp = a[i] * T.a[j] + ret.a[i + j] + up; if(temp > MAXN) { temp1 = temp  temp / (MAXN + 1) * (MAXN + 1); up = temp / (MAXN + 1); ret.a[i + j] = temp1; } else { up = 0; ret.a[i + j] = temp; } } if(up != 0) ret.a[i + j] = up; } ret.len = i + j; while(ret.a[ret.len  1] == 0 && ret.len > 1) ret.len; return ret; } BigNum BigNum::operator/(const int & b) const { BigNum ret; int i,down = 0; for(i = len  1 ; i >= 0 ; i) { ret.a[i] = (a[i] + down * (MAXN + 1)) / b; down = a[i] + down * (MAXN + 1)  ret.a[i] * b; } ret.len = len; while(ret.a[ret.len  1] == 0 && ret.len > 1) ret.len; return ret; } int BigNum::operator %(const int & b) const { int i,d=0; for (i = len1; i>=0; i) { d = ((d * (MAXN+1))% b + a[i])% b; } return d; } BigNum BigNum::operator^(const int & n) const { BigNum t,ret(1); int i; if(n<0) exit(1); if(n==0) return 1; if(n==1) return *this; int m=n; while(m>1) { t=*this; for( i=1;i<<1<=m;i<<=1) { t=t*t; } m=i; ret=ret*t; if(m==1) ret=ret*(*this); } return ret; } bool BigNum::operator>(const BigNum & T) const { int ln; if(len > T.len) return true; else if(len == T.len) { ln = len  1; while(a[ln] == T.a[ln] && ln >= 0) ln; if(ln >= 0 && a[ln] > T.a[ln]) return true; else return false; } else return false; } bool BigNum::operator >(const int & t) const { BigNum b(t); return *this>b; }
int main() { std::ios::sync_with_stdio(false); int k; std::cin >> k;
while(k) { int n; std::cin >> n; BigNum total_sum{0}; BigNum prefix_sum{1}; while(n) { int num; std::cin >> num; prefix_sum = prefix_sum * BigNum{num}; total_sum = total_sum + prefix_sum; } std::stringstream string_stream{}; string_stream << total_sum; std::cout.flush(); int digit_sum = 0; for(auto c : string_stream.str()) { digit_sum += c  '0'; } while(static_cast<int>(std::log10(digit_sum)) + 1 > 1) { int new_sum = 0; while(digit_sum != 0) { new_sum += digit_sum % 10; digit_sum /= 10; } digit_sum = new_sum; } std::cout << digit_sum << std::endl; } return 0; }
