同一个代码，第一次交90分，错第7个，我想了想又交了一次，结果过了。。。离谱，这是什么原理

#include<iostream>
#include<cstring>
using namespace std;
int main() {
	int n, m;
	cin >> n >> m;
	char s[105][105];
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++)cin >> s[i][j];
	}
	for(int i=1;i<=n;i++)
		for (int j = 1; j <= m; j++) 
			if (s[i][j] != '*') {
				int sum = 0;
				if (s[i - 1][j] == '*')sum++;
				if (s[i + 1][j] == '*')sum++;
				if (s[i][j - 1] == '*')sum++;
				if (s[i][j + 1] == '*')sum++;
				if (s[i - 1][j - 1] == '*')sum++;
				if (s[i - 1][j + 1] == '*')sum++;
				if (s[i + 1][j - 1] == '*')sum++;
				if (s[i + 1][j + 1] == '*')sum++;
				s[i][j] = sum + '0';
			}
	for (int i = 1; i <= n; i++) {
		for (int j = 1; j <= m; j++)cout << s[i][j];
		cout << endl;
	}
	return 0;
}