/*
ID: ruhansa1
TASK: gymnastics
LANG: C++
*/
#include <iostream>
#include <fstream>
#include <string>
using namespace std;
int k;
int n;
int counter=0;
int main() {
//freopen("gymnastics.in", "r", stdin);
//freopen("gymnastics.out", "w", stdout);
cin >> k >> n;
int pairs[k][n];
int comparing[n];
string xVal[k*n];
int yVal[k*n];
for (int j=0;j<k;j++){
for(int i=0; i<n; i++){
cin >> comparing[i];
//cout << comparing[i] << " ";
}
for(int i=0; i<n; i++){
if(i>0)
xVal[i]=to_string(comparing[i])+ "_"+ to_string(comparing[i-1]);
cout << xVal[i] << " ";
}
cout << "---";
}
/* for(int i=0; i<k-1; i++){
for(int j=0; j<n-1; j++){
for(int l=0; l<n-1; l++){
cin >> pairs[i][j];
if(pairs[i][j]==comparing[i][j])
counter++;
}
}
}
*/
//cout << 2*counter << endl;
return 0;
}
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