/*
 Ford-Fulkerson Algorithm
*/

#include <cstdio>
#include <cmath>
#include <cstring>
#include <iostream>
#include <vector>
#include <string>
#include <algorithm>
#include <queue>
#include <stack>
#include <set>
#include <map>
#define MAX_N 500
#define INF 987654321
using namespace std;
typedef long long lld;

struct Node
{
    vector<int> adj;
};
Node graf[MAX_N];
bool mark[MAX_N];
int cap[MAX_N][MAX_N];
int parent[MAX_N];

int v, e;
int s, t;

//Ford-Fulkersonov algoritam za nalazenje maksimalnog protoka izmedju dva cvora u grafu
//Moze se koristiti i za nalazenje maksimalnog matchinga
//Slozenost: O(E * maxFlow)

inline int DFS()
{
    int ret = 0;
    for (int i=1;i<=v;i++) parent[i] = 0;
    stack<int> dfs_stek;
    stack<int> minCapacity;
    parent[s] = -1;
    dfs_stek.push(s);
    minCapacity.push(INF);
    while (!dfs_stek.empty())
    {
        int xt = dfs_stek.top();
        int mt = minCapacity.top();
        dfs_stek.pop();
        minCapacity.pop();
        if (xt == t)
        {
            ret = mt;
            break;
        }
        for (int i=0;i<graf[xt].adj.size();i++)
        {
            int xt1 = graf[xt].adj[i];
            if (cap[xt][xt1] > 0 && parent[xt1] == 0)
            {
                dfs_stek.push(xt1);
                minCapacity.push(min(mt,cap[xt][xt1]));
                parent[xt1] = xt;
            }
        }
    }
    if (ret > 0)
    {
        int currNode = t;
        while (currNode != s)
        {
            cap[parent[currNode]][currNode] -= ret;
            cap[currNode][parent[currNode]] += ret;
            currNode = parent[currNode];
        }
    }
    return ret;
}

inline int FordFulkerson()
{
    int flow = 0;
    while (true)
    {
        int currFlow = DFS();
        if (currFlow == 0) break;
        else flow += currFlow;
    }
    return flow;
}

int main()
{
    v = 4, e = 5;
    s = 1, t = 4;

    graf[1].adj.push_back(2);
    graf[2].adj.push_back(1);
    cap[1][2] = 40;

    graf[1].adj.push_back(4);
    graf[4].adj.push_back(1);
    cap[1][4] = 20;

    graf[2].adj.push_back(4);
    graf[4].adj.push_back(2);
    cap[2][4] = 20;

    graf[2].adj.push_back(3);
    graf[3].adj.push_back(2);
    cap[2][3] = 30;

    graf[3].adj.push_back(4);
    graf[4].adj.push_back(3);
    cap[3][4] = 10;

    printf("%d\n",FordFulkerson());

    return 0;
}