zoj 2857 Image Transformation

#include "iostream"#include "vector"using namespace std;int main(){int N, M, casecount = 0;while (cin >> N >> M && N != 0 && M != 0){vector<int>r;vector<int>g;vector<int>b;int red, green, blue, ans;casecount++;for (int i = 0; i < N * M; i++){cin >> red;r.push_back(red);}for (int i = 0; i < N * M; i++){cin >> green;g.push_back(green);}for (int i = 0; i < N * M; i++){cin >> blue;b.push_back(blue);}cout << "Case " << casecount << ":" << endl;for (int i = 0; i < N * M; i++){ans = (r[i] + g[i] + b[i]) / 3;if ( (i + 1) % M)cout << ans << ",";elsecout << ans << endl;}}}