文件目录

#include <iostream>
using namespace std;
int f[40050];
int n, m;
void init()
{
    for (int i = 1; i <= 40000; i++)
        f[i] = i;
}
int findr(int x)
{
    if (f[x] != x)
        f[x] = findr(f[x]);
    return f[x];
}
bool mset(int a, int b)
{
    int fa = findr(a);
    int fb = findr(b);
    if (fa != fb)
    {
        f[fa] = fb;
        return false;
    }
    else
        return true;
}
int getnum(int x, int y)
{
    return (x - 1) * n + y; // 二维变一维
}
int main()
{
    init();
    cin >> n >> m; // 3 5
    for (int i = 1; i <= m; i++)
    {
        int x, y;
        char c;
        cin >> x >> y >> c;
        int a = getnum(x, y);
        int b = 0;
        if (c == 'D')
            b = getnum(x + 1, y);
        else
            b = getnum(x, y + 1);
        if (mset(a, b))
        {
            cout << i;
            return 0;
        }
    }
    cout << "draw";
    return 0;
}