Root of the Problem

                            Solution in C :

#include <stdio.h>

int main(void) {
	int t, n, id_sum, sid_sum, x, y;
	scanf("%d", &t);
	while(t--) {
	    scanf("%d", &n);
	    id_sum = 0, sid_sum = 0;
	    while(n--) {
    	    scanf("%d %d", &x, &y);
    	    id_sum += x;
    	    sid_sum += y;
	    }
	    printf("%d\n", id_sum - sid_sum);
	}
	return 0;
}
                        

                        Solution in C++ :

#include <iostream>
#include<bits/stdc++.h>
using namespace std;

#define ll long long int


int main() {
	ll t;
	cin>>t;
	for(ll z=1;z<=t;z++){
		ll n;
		cin>>n;
		int ans=0;
		for(int j=1;j<=n;j++){
			
			int x,y;
			cin>>x>>y;
			ans+=(x-y);
		}
		cout<<ans<<'\n';
	}
	return 0;
}
                    

                        Solution in Java :

/* package codechef; // don't place package name! */

import java.util.*;
import java.lang.*;
import java.io.*;

/* Name of the class has to be "Main" only if the class is public. */
class Codechef
{
	public static void main (String[] args) throws java.lang.Exception
	{
		// your code goes here
		Scanner sc = new Scanner(System.in);
		int t = sc.nextInt();
		while(t-- > 0)
		{
		    int n = sc.nextInt();
		    int node = 0;
		    int idsum= 0;
		    for(int i=0;i<n;i++)
		    {
		        node = node + sc.nextInt();
		        idsum = idsum + sc.nextInt();
		    }
		    int r = node - idsum;
		    System.out.println(r);
		}
	}
}
                    

                        Solution in Python : 
                            
# cook your dish here
t=int(input())
for _ in range(t):
    n = int(input())
    root = 0
    for j in range(n):
        ide,c = map(int,input().split(' '))
        root +=ide - c
        
    print(root)