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| #include<bits/stdc++.h>
#define ll long long
#define ull unsigned long long
#define maxn 1000005
#define put() putchar('\n')
#define Tp template<typename Ty>
#define Ts template<typename Ty,typename... Ar>
using namespace std;
inline void read(int &x){
int f=1;x=0;char c=getchar();
while (c<'0'||c>'9') {if (c=='-') f=-1;c=getchar();}
while (c>='0'&&c<='9') {x=x*10+c-'0';c=getchar();}
x*=f;
}
namespace Debug{
Tp void _debug(char* f,Ty t){cerr<<f<<'='<<t<<endl;}
Ts void _debug(char* f,Ty x,Ar... y){while(*f!=',') cerr<<*f++;cerr<<'='<<x<<",";_debug(f+1,y...);}
Tp ostream& operator<<(ostream& os,vector<Ty>& V){os<<"[";for(auto& vv:V) os<<vv<<",";os<<"]";return os;}
#define gdb(...) _debug((char*)#__VA_ARGS__,__VA_ARGS__)
}using namespace Debug;
int suf[maxn][3];
char s[maxn];
int ans;
inline int solve(int l,int r) {
int x,y,z;
x=suf[r][0]-suf[l-1][0];
y=suf[r][1]-suf[l-1][1];
z=suf[r][2]-suf[l-1][2];
int sum=(x==0)+(y==0)+(z==0);
if (sum==2) return 1;
if (x==y||y==z||z==x) return 0;
return 1;
}
signed main(void){
int i,j,n;
read(n);
scanf("%s",s+1);
for (i=1;i<=n;i++) {
if (s[i]=='B') suf[i][0]=suf[i-1][0]+1;else suf[i][0]=suf[i-1][0];
if (s[i]=='C') suf[i][1]=suf[i-1][1]+1;else suf[i][1]=suf[i-1][1];
if (s[i]=='S') suf[i][2]=suf[i-1][2]+1;else suf[i][2]=suf[i-1][2];
}
for (i=1;i<=3&&i<=n;i++) {
for (j=n;j>=i;j--) if (solve(i,j)) {ans=max(ans,j-i+1);break;}
}
for (i=n;i>=n-2&&i>=1;i--) {
for (j=1;j<=i;j++) if (solve(j,i)) {ans=max(ans,i-j+1);break;}
}
printf("%d",ans);
return 0;
}
|