#include <iostream> using namespace std; int main() { string a; cin>>a; int i=0; int len=a.size(); int count=0; for(i=0;i<len;i++) { if(a[i]!=',') { string b; while(i<len && a[i]!=',') { b+=a[i]; i++; } i--; int j=0; int len2=b.size(); int c=0; for(j=0;j<len2;j++) { c*=10; c+=b[j]-'0'; } if(count!=c) { cout<<count; return 0; } count++; } } cout<<count; return 0; }