1 #include <bits/stdc++.h>
2 #define _for(i,a,b) for(int i = (a),i##end=(b);i < i##end;i ++)
3 #define pb push_back
4 using namespace std;
5
6 int main()
7 {
8 int H,W,N;
9 while(~scanf("%d%d%d",&H,&W,&N))
10 {
11 int x = 0,y = 0;
12 int valid = 1;
13 _for(i,0,N)
14 {
15 char c;
16 cin >> c;
17 if(c=='U')
18 y ++;
19 else if(c=='R')
20 x ++;
21 else if(c=='D')
22 y --;
23 else if(c=='L')
24 x --;
25 if(x<0||x>=W||y<0||y>=H)
26 valid = 0;
27 }
28 if(!valid)
29 cout << "invalid";
30 else
31 cout << "valid";
32 }
33 return 0;
34 }
