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1.µÚÒ»ÖÖ·½Ê½，Ò»¸öÒ»¸ö´¦Àí：

char c;
while(~scanf("%c", &c)){
 if (c == '.'){
  putchar(c);
        }
}

while(scanf("%c", &c) != EOF) { }

while((c=getchar())!=EOF){ }