main(i,j,k,t,a){char s[101];a=99;gets(s);t=strlen(s);for(i=0;i<t;i++)if(s[i]==99)for(j=i+1;j<t;j++)if(s[j]==119)for(k=j+1;k<t;k++)s[k]==119&&a>k-i+1?a=k-i+1:0;printf("%d",a<99?a:-1);}