#include <cstdio>#include <cstring>#include <algorithm>using namespace std;const int way[8][3] = {{0, 1, 2},{3, 4, 5},{6, 7, 8},{0, 3, 6},{1, 4, 7},{2, 5, 8},{0, 4, 8},{2, 4, 6}};char s[10];bool check(char c){int i, j;for(i = 0; i < 8; ++i){for(j = 0; j < 3; ++j){if(s[way[i][j]] != c) break;}if(j == 3) return true;}return false;}int main(){int x, o;while(strcmp(gets(s), "end")){x = count(s, s + 9, 'X');o = count(s, s + 9, 'O');if(x < o || o+1 < x || x < 3) puts("invalid");else if(x > o && check('X') && !check('O')) puts("valid");else if(x == o && check('O') && !check('X')) puts("valid");else if(x + o == 9 && !check('X') && !check('O')) puts("valid");else puts("invalid");}return 0;}
