[模板] SAP

int dfs(int x,int flow){
    if(x==T) return flow;
    int tmp=res=0;
    for(int i=last[x];i;i=next[i]) if (d[x]==d[v[i]]+1 && w[i]>0){
        last[x]=i;
        tmp=dfs(v[i],min(flow-res,w[i]);
        res+=tmp;w[i]-=tmp;w[i^1]+=tmp;
        if (res==flow) return flow;
    }
    if (d[1]>=n) return res;
    vd[d[x]]--; if (vd[d[x]]==0) d[1]=n;
    d[x]++;vd[d[x]]++;
    last[x]=top[x];
        return res;
}  

int SAP{
    memset(d,0,sizeof(d));
    memset(vd,0,sizeof(vd);
    for (int i=1;i<=n;i++) last[i]=top[i];
    int ans=0;
    while (d[1]<n) ans+=dfs(S,1e9);
    return ans;
}