">int main() { int n; char a1, a2, a3, a4; scanf("%d %c %c %c %c\n", &n, &a1, &a2, &a3, &a4); char s[n]; for (int i = 0; i < n; i++) { scanf("%c", &s[i]); } for (int i = 0; i < n; i++) { if (s[i] == a1) s[i] = a2; if (...