#include <bits/stdc++.h>   using namespace std;   class abio {     static const unsigned BUF_SZ = 65536;     FILE *istream, *ostream;     char ibuf[BUF_SZ], obuf[BUF_SZ];     bool reached_eof;     size_t ip, isz;     size_t op, osz;     inline void clear_ibuf(void) { ip = isz = 0u; }     inline void clear_obuf(void) { op = osz = 0u; }     inline void clear_buffer(void) {       reached_eof = false;       clear_ibuf();       clear_obuf();     }     inline size_t read_buffer(void) {       isz = fread(ibuf, sizeof(char), BUF_SZ, istream);       ip = 0;       return isz;     }     inline size_t write_buffer(void) {       if (osz) {         size_t ret = fwrite(obuf + op, sizeof(char), osz - op, ostream);         op += ret;         if (op == osz) clear_obuf();         return ret;       }       return 0;     }     inline abio &reach_eof(void) {       reached_eof = true;       return (*this);     }       public:     static const char endl =   n ;     abio(FILE *input = stdin, FILE *output = stdout) {       this->istream = input;       this->ostream = output;       clear_buffer();     }     abio(const char *input, const char *output) {       this->istream = fopen(input,  r );       this->istream = fopen(output,  w+ );       clear_buffer();     }     ~abio(void) {       write_buffer();       fclose(istream);       fclose(ostream);     }     operator bool() const { return (!reached_eof); }     inline int getchar(void) {       if (0 == isz || isz == ip) read_buffer();       if (0 == isz || isz == ip) return EOF;       return ibuf[ip++];     }     inline int putchar(int ch) {       if (osz == BUF_SZ) write_buffer();       if (osz == BUF_SZ) return EOF;       return (obuf[osz++] = ch);     }     abio &read_int(int &x) {       int flag = 0, ch = getchar();       if (EOF == ch) return (this->reach_eof());       x = 0;       while ((EOF != ch) && (( -  != ch) && ((ch <  0 ) || (ch >  9 ))))         ch = getchar();       if (EOF == ch) return (this->reach_eof());       if ( -  == ch) {         flag = 1;         ch = getchar();       }       for (; (((ch >=  0 ) && (ch <=  9 ))); ch = getchar()) {         x *= 10;         x += (ch -  0 );       }       if (flag) x *= (-1);       return (*this);     }     abio &read_ll(long long int &x) {       int flag = 0, ch = getchar();       if (EOF == ch) return (this->reach_eof());       x = 0ll;       while ((EOF != ch) && (( -  != ch) && ((ch <  0 ) || (ch >  9 ))))         ch = getchar();       if (EOF == ch) return (this->reach_eof());       if ( -  == ch) {         flag = 1;         ch = getchar();       }       for (; (((ch >=  0 ) && (ch <=  9 ))); ch = getchar()) {         x *= (10ll);         x += (ch -  0 );       }       if (flag) x *= (-1);       return (*this);     }     abio &read_s(char *s, const char interrupt =    ) {       int ch = getchar();       while ((EOF != ch) && (ch <  !  || ch >  ~ )) ch = getchar();       if (EOF == ch) return (this->reach_eof());       for (; (EOF != ch) && (interrupt != ch) && (ch >=     && ch <=  ~ );            ch = getchar())         (*s++) = ch;       (*s) = 0;       return (*this);     }     abio &write_int(int x, char append = 0) {       int d[20], nd = 0;       if (0 == x) putchar( 0 );       if (x < 0) {         putchar( - );         x = -x;       }       while (x) {         d[nd++] = x % 10;         x /= 10;       }       while (nd--) putchar( 0  + d[nd]);       if (append) putchar(append);       return (*this);     }     abio &write_ll(long long int x, char append = 0) {       int d[20], nd = 0;       if (0 == x) putchar( 0 );       if (x < 0) {         putchar( - );         x = -x;       }       while (x) {         d[nd++] = x % 10;         x /= 10;       }       while (nd--) putchar( 0  + d[nd]);       if (append) putchar(append);       return (*this);     }     abio &write_s(const char *s, char append = 0) {       while (*s) putchar(*s++);       if (append) putchar(append);       return (*this);     }     abio &operator>>(char &ch) {       ch = getchar();       if (EOF == ch) return (this->reach_eof());       return (*this);     }     abio &operator>>(int &x) { return read_int(x); }     abio &operator>>(long long int &x) { return read_ll(x); }     abio &operator>>(char *s) { return read_s(s); }     abio &operator<<(const char ch) {       putchar(ch);       return (*this);     }     abio &operator<<(const int x) { return write_int(x); }     abio &operator<<(const long long int x) { return write_ll(x); }     abio &operator<<(const char *s) { return write_s(s); }   } io;   int n, s[100005];   int main() {     io >> n;     if (n > 26 || n < 2) {       io <<  Yes n  << io.endl;       return 0;     }     while (n--) {       char c;       io >> c;       s[c -  a ]++;       if (s[c -  a ] > 1) {         io <<  Yes n  << io.endl;         return 0;       }     }     io <<  No n  << io.endl;     return 0;   }