Tunnels

#include <bits/stdc++.h>
#define SZ(x) ((int) (x).size())
using namespace std;

typedef long long int64;

const int NMAX = 100000;

int degree[2][NMAX];

int main(void) {
    cin.tie(0);
    ios_base::sync_with_stdio(false);
    
    int n, m; cin >> n >> m;
    for (int i = 0; i < m; i++) {
        int from, to; cin >> from >> to;
        degree[0][from - 1]++;
        degree[1][to - 1]++;
    }
    
    int answer = 0;
    for (int i = 0; i < n; i++) {
        answer += abs(degree[0][i] - degree[1][i]);
    }
    cout << answer / 2 << '\n';
    return 0;
}

Test 1

Group: 1

Verdict: ACCEPTED

Test 2

Group: 1

Verdict: ACCEPTED

Test 3

Group: 1

Verdict: ACCEPTED

Test 4

Group: 1

Verdict: ACCEPTED

Test 5

Group: 1

Verdict: ACCEPTED

Test 6

Group: 2

Verdict: ACCEPTED

Test 7

Group: 2

Verdict: ACCEPTED

Test 8

Group: 2

Verdict: ACCEPTED

Test 9

Group: 2

Verdict: ACCEPTED

Test 10

Group: 2

Verdict: ACCEPTED

Test 11

Group: 3

Verdict: ACCEPTED

Test 12

Group: 3

Verdict: ACCEPTED

Test 13

Group: 3

Verdict: ACCEPTED

Test 14

Group: 3

Verdict: ACCEPTED

Test 15

Group: 3

Verdict: ACCEPTED