//temp_0x00000001.cpp
//To verify the 13th on the mathematics (of science subjects) paper of the Exam of the Union of "Known Schools in Northern Anhui". - Quick programming
//DEBUGGING ON codepad

#include <iostream>
using namespace std;

int main() {
    int i=1, S=0, n[4]={1, 0, -1, 0};
    cout<<"#init: i="<<i<<", S= "<<S<<"\n";
    do {
         cout<<"#S="<<S<<"+"<<(n[i%4])<<"=";
        S+=n[i%4];
        cout<<S<<"\n";
        cout<<"#i="<<i<<"+1"<<"=";
        i++;
        cout<<i<<"\n";
    } while (!(i>5));
    cout<<"#Result: S="<<S<<"\n";
    return 0;
}

#init: i=1, S= 0
#S=0+0=0
#i=1+1=2
#S=0+-1=-1
#i=2+1=3
#S=-1+0=-1
#i=3+1=4
#S=-1+1=0
#i=4+1=5
#S=0+0=0
#i=5+1=6
#Result: S=0