#include<stdio.h>
#include<string.h>
#include<ctype.h>
#define MAX 100000
char stack[MAX];
int top=-1;
void push(char c){
 if(top<MAX-1){
     stack[++top]=c;
 }   
}
char pop(){
    if (top>=0){
        return stack[top--];
    }
    return -1;
}
char peek(){
    if(top>=0)return stack[top];
    return -1;
}
int isOpening(char c){
    return (c=='(' || c=='[' || c=='{');
}

int isclosing(char c){
    return (c==')' || c==']' || c=='}');
}
int isMatching(char open,char close ){
    return((open =='('&&close==')')||
    (open =='['&&close==']')||
    (open =='{'&&close=='}'));
}
int isAllowChar(char c){
    return (isdigit(c)||c=='+'||c=='-'||c=='*'||c=='/'||
    c=='('||c==')'||c==')'||c=='['||c==']'||
    c=='{'||c=='}'||isspace(c));
}
int isValidSequence(char *exp){
    int len=strlen(exp);
    for(int i=0;i<len;i++){
        char c=exp[i];
        if(!isAllowedChar(c)){
            return -1;
        }
        if (isOpening(c)){
            push(c);
        }
        else if(isClosing(c)){
            if(top==-1||!isMatching(pop(),c)){
                return 0;
            }
        }
    }
    if (top!=1){
        return 0;
    }
return 1;
    
}
int main(){
    char expression[MAX];
    if(!fgets(expression,sizeof(expression),stdin)){
        printf("Invalid input\n");
        return 0;
    }
    int result=isValidSequence(expression);
    if(result==-1){
        printf("Invalid input\n");
        
    }
    else if(result ==0){
        printf("Invalid sequence\n");
    }
    return 0;
}