scanf("%d%d", &n, &m);
		for (int i = 1; i <= m; i++) {
			cin >> ch >> x;
			sum[x] = ch - 'A';
		}
		int ans = 0;
		for (int i = 1; i <= n; i++) {
			if (char(sum[i] + 'A') == 'U') {
				ans++;
			}
		}
		printf("%d\n", ans);

请问思路对不对。